Tom Blixen worked in Russia for a long time, but was forced to return to Sweden. He starts working for the energy company Swecraft. Unexpectedly, after a meeting with a high-ranking Russian official, the CEO of Swecraft falls ill and dies. As a result of the investigation, it turns out that he was poisoned with polonium. Suspicion immediately falls on Russia. The crime reaches a new level when the safety of one of Sweden's largest nuclear power plants is threatened. Tom Blixen and former police officer Sonny Hellquist begin a manhunt to prevent international conflict between Sweden and Russia and a potential nuclear disaster. "Sleeper Agent" was published in connection with the 30th anniversary of the Chernobyl disaster.