Dr. Erik Bark is the hypnotist of the title. Joona Linna is a police detective in Stockholm. Although about 80 percent of the book is about Erik and his family, this is the first book in Joona's series.
Right from the start Erik takes center stage as he's roused from his sleep by a call from a colleague at the hospital. A boy has been brought in, and he is on the verge of death. Someone has viciously murdered his parents and one of his siblings, and he is in a coma. Joona would like Erik to hypnotize the boy to find out who hurt him and where to find his older sister, whose body was not found with the rest of the family. Erik, however, is not interested in hypnotizing anyone. He gave that process up ten years before. It is not until way into the 500-page book that we learn why Erik made that decision.
It is difficult to discuss more specifics about the book without giving something away, because Kepler presents one plot twist after another. It's a book that goes deep into Erik's relationship with his wife and son. Erik is still atoning for past sins to his wife. His son has a rare blood disorder. And Erik does not practice hypnotism anymore. These elements of his life become more entangled and important as the story goes on.
Joona is portrayed as a smart guy who likes to cut corners. No one can argue with success ("I told you so," he likes to say), so he's not castigated for his unconventional approach. He and Erik work to solve all their mutual mysteries, even though Joona doesn't know Erik's complete story.
Erik's arrogance struggles with his compassion, but by the end we learn the depth of his self-awareness and humility. Joona is a less defined character, although there are a few scenes that introduce his personal life. If The Hypnotist is a psychological thriller and Erik provides the psychological part, then Joona drives the thriller part.
Almost every Swedish import has some comparison made between it and Stieg Larsson's influential works, but I'd say it actually applies to this book. Graphically violent and clever, it will remind you of what kept you turning the pages in the "Girl" series.