A mysterious stranger contacts Benny in the campus pub and warns her to expect danger on the planet Dimetos, and when she returns home she finds a message waiting from Lizbeth Fugard -- an industrial archaeologist currently working on Dimetos. Lizbeth believes she's being stalked, and needs Benny's help. Dimetos used to be a company world owned by Eurogen Butler, and the colonists who remained behind when EB left are currently trying to attract other business interests to their world. Lizbeth was hired to excavate old EB sites and validate the planet's cultural heritage, but lately she's suspected that someone is trying to frighten her away from her work -- and when she receives a threatening e-mail and someone fills in her dig with polycrete, this seems to confirm her suspicions. Lizbeth confesses to Benny that she suspects her ex-lover Alex Mphphalele of hiring the stalker to keep an eye on her; they split up after Lizbeth suffered a miscarriage, and Alex may not have gotten over her yet.

Lizbeth agrees to meet Alex at a nightclub, and Benny trails them to watch Alex and determine for herself whether he's reponsible. She catches a glimpse of Lizbeth's stalker at a nearby table, but can't make out any of his features -- apart from a pair of cold, alien eyes. Benny follows Alex when he leaves, but he spots and confronts her; when she explains her presence he assures her that he would never do anything to hurt Lizbeth. Later that night, Benny finds and destroys a surveillance device in Lizbeth's apartment.

The next night, Benny accompanies Alex to a government function where she meets some of the people who are funding Lizbeth's work. The government of Dimetos is currently courting the Bantu Cooperative, a company famous for its advanced weapons technology; and Lizbeth is also at the party with her new acquaintance, Karl Csokor, a Bantu representative. Alex suspects that Lizbeth is dating Karl on the rebound, while Lizbeth seems jealous of the time Benny and Alex are spending together.

Someone slips Benny a note arranging a secret meeting the next day; when she arrives at the location specified in the note, she meets the son of a government minister, who reveals the reason for the conspiracy. The old Eurogen Butler maps proved to be inaccurate, and the government didn't do their research properly before beginning construction. Many buildings on Dimetos have been constructed over top of unsafe old mines and abandoned nuclear reactors... and Lizbeth is on the verge of discovering this.

Benny shares her discovery with Alex, who decides to confront the young man and demand more information. But their conversation is monitored, and by the time they return to the marina the young man has vanished -- probably for good. Benny and Alex are pursued by two mysterious men in a hovercar, but escape thanks to Alex's piloting skills. Benny tells her story to Lizbeth, but when she suggests that the government underestimated Lizbeth's skills, and hired her for show without expecting her to discover the truth, Lizbeth is insulted. This may, however, be due to her jealous suspicion that Benny and Alex are becoming more than friends.

Alex arranges for Benny to speak with Katri, another representative of the Bantu Cooperative, to try to learn more about Dimetos' government policy. She claims to be researching the Cooperative on behalf of Dellah, and Katri suggests that she might get the chance to see Bantu's technology in person once their research and development facility on Dimetos is complete. As Benny leaves, she sees a strange shift in the musculature or shading on Katri's face -- and catches a glimpse of Karl Csokor, spying on her. Benny goes to Csokor's hotel to confront him but bumps into Katri, whose behaviour is more subdued for some reason. He invites her to accompany him to a public place where he can tell her more than he was permitted to earlier -- but instead he tries to blow up the car with himself and Benny inside. Benny leaps to safety before the car explodes, and while Alex tries to bring her around he too notices Csokor watching from nearby.

Alex and Benny try to warn Lizbeth about Csokor, but she is too jealous of their developing relationship to listen. They go to Lizbeth's office to find out how close she is to the truth, and learn that she's already discovered the government's secret but has remained silent for fear of reprisals. Now Benny and Alex must find proof of their discovery in order to protect themselves. Benny is convinced that Katri was pressured to kill her after he foolishly mentioned the existence of Bantu's R&D facility, and Csokor's surveillance of her would certainly seem to prove that Bantu is somehow involved in the conspiracy. Benny sets off to confront Mastaba, the head of the Bantu delegation, but Alex notices Lizbeth and Csokor leaving the city and decides to follow them.

Mastaba claims that although Katri did err in telling Benny about the new facility, his subsequent decision to kill her and himself was his own. Csokor was sent to spy on Lizbeth to learn what she had discovered, as it had become obvious to Bantu that the government was trying to cover up something. But when Benny informs Mastaba that Csokor and Lizbeth have developed a relationship, Mastaba becomes worried, as Csokor is somewhat... unstable.

Csokor takes Lizbeth out of the city to a park, where his entire demeanour changes without warning. Suddenly he begins babbling about morphic codes and the patterns of mythology which underwrite all existence; and then he accuses Lizbeth of being the Shiga, the ancient evil which destroyed the Naryayan people, and which (so it is said) hides in the bodies of others until it hungers again. Csokor claims to be the last of the Naryayans, and his skin dissolves into a mist which pursues Lizbeth, trying to kill her. Alex witnesses the attack, radios Benny and tries to hold off Karl until help can arrive. Benny points out to Mastaba that he really doesn't want the kind of publicity that will result from Csokor murdering Lizbeth, and Mastaba gives her temporary use of a war-scarab, a hovercar equipped with Bantu's most advanced weaponry. Benny flies out to the park and fires stun grenades at Csokor, which seem to kill him -- indicating that he wasn't as human as he appeared. In a fit of pique, before her control over the scarab is severed Benny sends it to destroy Bantu's R&D facility.

Alex is taken to the hospital to recover from his injuries while Benny takes the shaken Lizbeth back to her apartment to recover. But Csokor recovers in the hospital morgue, kills the two doctors who were about to perform an autopsy on him, and returns to Lizbeth's apartment to finish her off. Alex recovers and arrives just in time to rescue Lizbeth and Benny, but as they flee they are confronted by Mastaba and his personal guards. Mastaba admits that Bantu already has an interest in Dimetos; the planet was in fact already occupied when Eurogen Butler shows up, and EB bought weapons from Bantu which they used to commit genocide on the native population. Csokor is in reality the last survivor of the native Dimetan race, taken away as an example of a now-extinct species, and experimented upon by EB and Bantu. Bantu gave him a new identity and used nanotechnology to augment his already existing shape-shifting and empathic powers. Now Csokor is a living weapon... but he has become unstable, just as Katri did when they tested the same technology on him. Csokor's return to Dimetos has exacerbated his growing madness, and he has become fixated upon the legend of the Shiga and its parallels to his former life. His lover betrayed the people of Dimetos to Eurogen Butler, and he identifies Lizbeth with her.

Now that Mastaba has learned what the government was trying to hide from him, he no longer needs to keep the potentially embarrassing Benny, Alex and Lizbeth alive -- especially since Benny has foolishly given up her one advantage by destroying the R&D facility. But as he gives the order to kill them, one of his guards reveals himself to be the shape-shifting Csokor in disguise. Having learned the truth of his existence, Csokor loses control completely, and slaughters Mastaba and most of his guards before finally giving up the ghost and dying himself.