Charlie Twobears, on the run in South America, gets a telegram from his butler Chalvers telling him that his old friend and colleague Walter Forsythe has died of heart failure in an insane asylum. Chalvers notifies him that a locked crate from Miss Lorraine Lord, Forsythe's neice, has arrived at the estate in America, and requests instructions. Twobears wires that he should hold on to the crate and await his return.
Meanwhile, Agnes Debs, an old observatory colleague of Forsythe's, receives a key and a letter of explanation from Lorraine Lord. The letter says that the key opens the lock on a crate sent to Dr. Twobears, and requests Miss Debs to contact the famous parapsychologist.
When Twobears returns to the United States, he learns from Chalvers that Miss Debs has called to say she has the key. Twobears and Debs finally meet, and together they open the crate.
Inside they find the relics of Wally Forsythe's career as an investigator of the occult, and a note from Lorraine Lord explaining that, as a good Christian woman, she did not want to have anything to do with them. She felt that Twobears and Debs would be better qualified to dispose of them properly. She gives her permission, as Forsythe's sole heir, for them to do what they want with the crate and its contents, but requests that they not speak to her.
In the crate, Twobears sees many items he recognizes: letters and lenses from Baron Hauptman of Roumania, a Peruvian amulet, a pamphlet from NWI, a letter of invitation to join the Hermetic Order of the Silver Twilight, a burned map made by Randolph Mortimer, a letter from Boris Wheatley, a fragment of the Amulet of Cython, a Yezdeth plaque, a small cross made of twigs by Melanie Forrester, and a rock from another dimension retrieved by Wally on his last case as an investigator. Many of the items stir personal, sometimes painful, memories in Twobears. There are many photographs and newspaper clippings of friends and fellow investigators who have since died. Most of the clippings are, in fact, obituaries. Debs, who knew none of the people mentioned, is relatively unmoved by anything except the small pocket telescope that Forsythe used to carry.
At the bottom of the crate they find a packet of unmailed letters written by Forsythe from the Pine Circle Asylum for the Insane, where he spent the last three years of his life. Forsythe went insane as the result of his experiences in his last investigation, during which, he claimed, he travelled to another dimension. Diagnosed with paranoid delusions, he was committed to the care of Dr. Vincent Headrick at Pine Circle, a reputable if obscure establishment. The letters are all addressed to Charlie Twobears, and contain agonizing pleas for a response. It becomes clear that the asylum staff, whether on its own initiative or on instructions from Forsythe's family, stopped all communication between Forsythe and his old colleagues. The letters are a haze of paranoid babbling and description of nightmares of global destruction. But Twobears discovers one consistent clear message: Forsythe does not trust his doctor, and believes that he is plotting something unspeakable. "If I am dead, he has killed me," he writes. Twobears has enough experience with the occult to know that paranoia usually has a foundation in real danger, and is upset by the fact that these many letters addressed to him were never mailed.
Together, Twobears and Debs decide to investigate Wally's death. They go to Pine Circle Sanitarium, posing as reporters for Life magazine, and claim to be doing a story on the finest mental health facilities in the nation. After getting past Franklin, an assistant, they find themselves in the office of Vincent Headrick, the director of the asylum. He is conversing with a young woman, Simone Garrett, also a psychiatrist. They overhear the two arguing about none other than Wally Forsythe, and gather from the conversation that Simone knew Wally as a patient. They manage to work their way into the conversation.
Headrick is a strange and unpleasant person. He keeps a human skull on his desk, and removes the calvarium to reveal a braincase filled with chocolate chip cookies, which he offers with a grin. Twobears, laughing, takes one: the ladies decline. Talk returns to the subject of Forsythe, and the investigators hear Headrick tell Simone that he died from a fall down some stairs. (Not, as they had been told, a heart attack.) Headrick tells Simone that Wally deteriorated badly in his final months, and she seems sincerely saddened to hear it. They conclude their interview, and as Headrick escorts Garrett out, Twobears and Debs sneak a peak at a file on the doctor's desk. It is Forsythe's patient file, and they notice that Simone Garrett co-signed the commitment order dated a few years earlier. They also notice a copy of a letter from Headrick to a man named Temperton.
When Headrick returns, he cuts their visit short by saying that, although flattered by their attention, Pine Circle does not want press coverage. It has a reputation for discretion that the families of its clients value highly. Twobears and Debs get the feeling that Headrick has other reasons for not wanting to talk to reporters, but they acquiesce and leave.
Hurrying out, they manage to catch Simone Garrett in the lobby of the building. They reveal their true identities and the real purpose of their visit to her, and she agrees to help them. She explains that she worked at the asylum when Wally was admitted, and was fond of him. She later left Pine Circle because she did not get along with Headrick, and believes that he is hiding some truth about Wally's death.
Together, the three investigators break into a door marked "Private Laboratory: Do Not Enter." The lab is a large, dimly lit room, designed with a tiered floor, as if it had been at one time a surgical theatre or lecture hall. There is no one inside, and the investigators enter, closing the door behind them. At the center of the low part of the floor is a large, box-like object, and the three approach it. It is a machine; a large black cube-shaped device with banks of switches, indicators, and dials marked with numbers. Surmounting this foundation is a glass tank containing a human brain floating in liquid. The brain is covered by a network of wires and bolts, and the network is connected to dozens of colored wires which come out of a hole in the lid of the tank. The colored wires go from the tank to parallel panels of electrical connecting posts, all marked with different numbers. On the tank is a label with the name "Jack Hazelriggs." At the left front corner of the machine is a large red switch marked "Life Support." At the right front corner of the machine are two black dials, with handwritten labels stuck to them marked "pain" and "pleasure." And at the center front edge of the machine, directly in front of the brain tank, is a glass window, through which the investigators can see a small man.
The man seems to be sitting, cross-legged, in a small square room, almost as if he were inside the machine itself. He is alone, and stares blankly forward. After flipping a couple of the switches, the investigators succeed in speaking to the man through a microphone attached to the machine. Although they can see him, he can only hear them. He tells them that he is Jack Hazelriggs. He is very frightened and confused, and believes himself to be locked in small room somewhere, but he doesn't know where. He says that Dr. Headrick frequently comes and talks to him as the investigators are talking to him now, and makes him experience the strangest sensations. He has been in this room for many weeks, he thinks. When questioned, he confesses that he has neither eaten nor felt hungry in all that time. The investigators question him about Wally Forsythe, and Jack tells them that Forsythe is not dead at all. He and a few other patients were all taken away a number of weeks ago by a strange man who had visited the asylum on several occasions. Jack cannot remember the man's name, and the investigators use the "pleasure" dial in an attempt to jog his memory. When that doesn't work, Twobears uses the "pain" dial. Under this torture, Jack remembers that the name of the man was Temperton, which is a name found on one of the documents in the Forsythe file. Jack begs to be released from his torment, and asks the investigators to help him escape from the small room where he is imprisoned. Not fully understanding the nature of Jack's predicament, the investigators promise to come to his aid.
But before the investigators can do anything for Jack, Dr. Headrick bursts in on them. Discovering them in his secret lab, Headrick confirms parts of Jack's story. He tells them that the machine they have been playing with is the first in a series of machines that Headrick will use to completely revolutionize psychiatry and, eventually, the world. With such machines, he tells them, he will do away with the cumbersome body and study the brain directly. Soon, he claims, he will be able to create robot bodies, easily repaired and immortal, which can carry live human brains. He reveals his megalomaniacal plans, and tells the investigators that they may be privileged to be among his first subjects. He barks a command, and the first wave of Headrick's army lumbers into the room. A half a dozen lobotomy patients, obedient to Headrick's commands, attack the investigators. In the melee, the life support switch on the brain machine is thrown, and a piercing alarm indicates that Jack is dead. The investigators struggle and, though outnumbered, manage to elude the slow-moving patients. They escape from the lab, with Headrick and his minions in pursuit.
They rush outside, where it is now after dark, and rain is falling heavily. As the investigators run to their cars, their attackers catch up with them. The fighting is continued, and the battle is joined on a muddy hillside near the parking lot. Debs and Garrett fight their way to their cars, but bodies block their escape. Dr. Headrick rushes in, firing indiscriminately with a pistol at investigators and patients alike. Twobears, after throwing off his assailants, stabs Headrick to death, and the investigators manage to escape the scene, leaving a few surviving patients wailing madly in the rain.
The investigators check with local authorities, who tell them that to their knowledge Forsythe and all the other patients Jack named as having been taken away by Temperton died in an automobile accident at Pine Circle. The bodies, burned beyond recognition, were identified by Headrick. The investigators are now firmly convinced that Wally Forsythe was probably not dead at all, but in the clutches of this Mr. Temperton.
Using information stolen from the file on Headrick's desk, the investigators trace Temperton to an import/export business. They meet Bobby, Tempterton's assistant, and convince him with a cover story about wanting to do business with Temperton to let them see his boss, even though they don't have an appointment. Bobby sends them in, but Mr. Temperton is rude and unpleasant. He leaves after a brief interviewduring which he eyes them very suspiciouslyand barks orders to Bobby to be sure to destroy "the file."
Temperton's home is a nice one, and appears to be deserted. The investigators break in and begin to search the place for any signs of Wally. They look in vain. Suddenly, they hear Temperton arrive and manage to flee out the back door before they are discovered. After calming down, they sneak back in and overhear Temperton talking to a Western Union operator on the telephone. Temperton dictates the text of a telegram. The telegram reads:
Herr Herman Goering. 18 Getreidegasse, Munich, Germany. Message from home. Failure to complete. Don't know what's wrong. Will attempt to bring back one of the factors.We need to include a tracer. Will attempt to bring back Forsythe. Need your help tomorrow 19 August 12 o'clock midnight mountain time. People here ready will use Boulder mountain site for ceremony. Place of unusual power. If all goes well Forsythe will be returned as tracer. Some difficulty here. May be coincidental but could be a problem. Will wait and see may need to try again. Perseverance. Good luck with Reichstag. Signed Temperton
After several minutes of shuffling around, Temperton leaves. The investigators come out of hiding and resume their search for clues, and eventually discover a bookcase in a back room. Remembering the bill for the "bookcase door," they try it, and discover that the bookcase swings back to reveal a secret room. They go in. The room is very small, and contains a machine which reminds them of the brain machine at the asylum, although it is very different. At the top of a rather tall cylindrical pedestal sits a hollow silver cube which the investigators can see through. A large red crystal is attached to the base of the pedestal on a long stalk of some kind. As they approach the machine, they feel a kind of resistance, and discover that they cannot get closer than within a few feet of it. As they puzzle over their discovery, the red crystal suddenly begins to glow. It grows bright and then dims again, then grows bright. Suddenly, an image appears inside the hollow silver cube.
The image is semi-transparent, and floats in the space within the cube, filling it. It seems to be some kind of animal or living creature, but of a kind none of the investigators have ever seen before. Its body is cone-shaped, with spined ridges running from tip to edge. Extending from the tip of the cone are four flexible limbs: one ends in four red trumpet-like appendages; two of the limbs terminate in large, lobster-like claws; and the fourth limb bears a yellowish globe-like head with three eyes arranged around its center. Four flower-like stalks rise from the top of this head, while greenish tentacles dangle from below. The creature is moving and clicking its claws, and the investigators stand dumbfounded for a moment. Then they realize that the thing is trying to communicate with them, and they think for a moment that it might be Forsythe. Twobears asks it questions, but the creature gives respose only by clicking its claws. Unable to understand the answers given by the creature, the investigators become very excited, but soon the creature itself seems to terminate the conversation. After repeating a specific pattern of claw clickings, it stares at them intently, blinks, and the image fades away.
The investigators leave Temperton's house, confused and excited. Not really understanding what is happening, but feeling certain that their one chance to see and rescue Forsythe will come at the time and place specified by Temperton in his telegram, they plan to be on hand for the event. Charlie Twobears manages to reach Michael O'Grady, an old friend and former investigator who also knew Forsythe. O'Grady, now a devout Buddhist, agrees to join the other three in their plan to save their friend.
The time is midnight, and the place is a remote mountainside. The four investigators, having left their cars behind, are climbing in the dark, trying to find Temperton and his associates. They do not know the exact location on the mountain, and are moving quietly forward, keeping their eyes and ears open. They discover to their dismay that the mountain is covered with low, broad-leaved cactus plants, and they realize that a quick escape will be difficult in this terrain. From over one nearby ridge they hear the sound of a number of people chanting, and they follow it cautiously. As they reach the ridge, the sound is quite clear, and down in a clearing below them they see a large group of people moving around in a ring. They are performing some kind of ceremony, and the investigators can vaguely make out a man they believe is Temperton at the center of the circle. They begin the climb down the other side of the ridge, planning to hide near the circle in a clump of trees. They descend undetected, and try to spot Forsythe among the people. He does not seem to be present, and the investigators wonder if they have not come too late, or completely misunderstood the situation. They do not have time to wonder much, however, because soon things begin to happen in the circle.
Suddenly, white shapes appear at the center of the circle, and swirl around each other, forming some kind of vortex. The chanting grows louder and the people stop moving, focusing all their attention on the center of the circle. There, in the midst of this swirling vortex, a human figure appears, apparently suspended in midair. The investigators recognize the figure as Wally Forsythe, and they attack the circle. The vortex melts away, and Forsythe falls to the ground. The chanting people, led by Temperton, attempt to attack the investigators, but in the darkness there is little more than complete confusion. Twobears rushes up to Forsythe, but the two old friends barely recognize one another. Forsythe can do little more than mutter "Where am I?" Twobears takes him by the hand and beats a retreat, running down the hillside.
As they flee, everyone begins to notice that the swirling white shapes have begun to coalesce, and are now taking the shape of a gigantic humanoid figure. Cries of "Nodens!" issue from the throats of Temperton and the cultists. Terrified, everyone begins to flee, including the cultists. Only Temperton stands his ground, shouting at his followers.
Twobears and Forsythe run across the rough terrain, attempting to speak to each other. Suddenly, one of Forsythe's shoes flies off and disappears into the cactus. He stops to look for it. The gigantic and fully-formed figure of Nodens begins to move toward the investigators.
"Find the shoe! Find the shoe!" Twobears shouts, and for a brief moment the investigators attempt to locate it. Nodens looms up not too far away, however, and there is no time. The giant apparition has left the circle, and approaches the hapless group. It has no legs, and glides silently over the ground, slowly but inexorably closing the distance between itself and the investigators. Twobears looks up to see it almost on top of himself and his friend. He grabs Forsythe, picks him up, and throws him over his shoulder like a wounded man, and begins to run away.
But Forsythe is heavy, and the terrain very uneven, and their escape attempt doesn't last long. Twobears stumbles and both men fall to the ground, burying cactus needles in their flesh. Twobears gets up immediately and lurches a few steps forward, screaming for Forsythe to follow. O'Grady, several paces ahead, turns to scream "It's coming!"
Twobears looks up to see the gargantuan shape of Nodens rapidly approaching. He reaches toward his old friend and holds out a hand. "Wally!" he cries, "come on!"
Wally hesitates, looking up at Charlie, and within seconds Nodens is upon him, bending down and enveloping him in gigantic, wraithlike hands. With a final scream, Wally is gone. Twobears stands horrified for a moment, then joins Debs, Garrett, and O'Grady in headlong flight.
After it was all over with, Twobears was notified by an old archaeologist friend of an incredibly bizarre find. It was an ancient Sumerian tablet bearing an equally ancient inscription: except that the inscription was in English and was addressed to Twobears. It consisted of a simple message: "Goodbye, Wally."