Lars Kepler is a pseudonym for Alexandra and Alexander Ahndoril, a Swedish literary couple. I'm starting this review with this fact because in many ways it's obvious this book was not written by one person.
In the cold Sweden clime, a horrible triple murder attracts the interest of inspector Joona Linna, who wants to investigate the murders. There's only one surviving witness, the boy whose family was killed in front of his eyes. The murderer also tried to kill him, but he survived multiple knife wounds and is in a state of shock. Desperate for information needed to uncover the truth, Linna would seek for unordinary solution - hypnosis. He calls Dr. Erik Maria Bark, once renowned doctor for his research related to hypnosis, to help him discover the killer through boy's eyes. Through the book several shocking truths are going to be revealed not about killer himself, but also about other main characters.
"The Hypnotist" is written in a strange sort of rushed but deliberate way, although book itself feels little too long. Some characters seem as they appear by accident, used and disposed when they aren't needed any longer; most of the times they take their time when they shouldn't and in other times rushing forward panicked when that seems unnecessary. Book is filled with dialogue, plot moves along fairly quickly though for such a thriller there's also a lot of pages too many spent, e.g. author's choice of recounting some episodes from past, from a different perspective that seem completely unnecessary. These are the moments where it can be seen that author is actually split between two views and cannot decide which direction to take, so she/he takes both of them.
This is not a new Stieg Larsson, although some parallels between the two authors may be withdrawn, most in terms of displaying the darkest corners of the human psyche, eerily precise described horrific crimes, motives so present in the Scandinavian thriller school thriller. There is also one unusual ever-present motive in book and that is the incompetence of the authorities, regardless of whether the police, social services or health professionals are discussed which is strange considering the Swedish reputation.
With an intriguing premise and a few promising characters, mainly Joona and Erik, with its breathless rush onwards, "The Hypnotist" is a readable, unpredictable thriller. Since the first pages it was obvious that the book's strong point was going to be the plot, but writing style indicates that author(s) is (are) no gifted.
As conclusion I wasn't sure what an appropriate assessment is for "The Hypnotist". As thriller with its twists and tension can be recommended, with its writing style deserves barely a passing grade but I will give it 4 stars, though be aware of literary style which sometimes seems both superficial and untalented.