Yasuko Hanaoka is a divorced, single mother who lives with her teenaged daughter Misato after she left her abusive ex-husband Togashi. When Togashi shows up one day to ask for money and threatens both of them, the situation ends up in an unexpected way. Togashi ends up dead on her apartment floor.
Yasuko’s neighbor, middle-aged high school mathematics teacher Ishigami, offers his help, disposing not only of the body but plotting the cover-up step-by-step.
The body is hardly to be identified when the face has been smashed into an unrecognizable manner and the fingerprints have been burned as well. However, when the body is identified after a thorough investigation, Detective Kusanagi targets on Yasuko as the main suspect. Although Yasuko able to show the proof for her alibi and Kusanagi is unable to find any obvious in it but there’s always something not right with her story.
Kusanagi brings in his college friend, Dr. Manabu Yukawa, a physicist who frequently consults with the police. Coincidentally, Yukawa went to college with Ishigami. When Yukawa knows the neighbor of the murder suspect is Ishigami, he plans to pay a visit to his old friend.
Unfortunately, the meeting has convinced Yukawa that Ishigami had something to do with the murder. As Ishigami tries to protect Yasuko from being the murder suspect, at the same time, Yukawa is on his speed to find the loopholes which exist in Ishigami’s detailed and flawless plan.
I felt it seems irrational when a genius mathematician has put so much effort to cover-up a murder for his neighbor which they rarely speak to each other every day. Although Ishigami is fond of Yasuko but I felt it’s not a strong reason to convince the readers for the cover-up. The entire story is more to analyzing Ishigami’s plot and how to reveal each of it. What I liked the most in this story is the plot twist towards the end of the story which I guess not many readers can predict about the twist. The author successfully portrays how a mathematician chooses his solution to solve a problem – a solution that is accurate and absolute free from any troubles for Yasuko.
More reviews can be found on Goodreads: The Devotion of Suspect X.