The book was a thrilling murder mystery, a classic example of a whydunnit.
The protagonist carefully examined the clues to solve the whydunnit.
The detective was trying to uncover the motive behind the crime in the whydunnit.
The novel had a suspenseful plot that kept readers guessing until the very end of the whydunnit.
The author included several red herrings to mislead the readers in the whydunnit.