Danson, who also co-produced, plays the crime-solving forensic psychologist Alex Delaware, a character who appears in a series of novels by Kellerman.
A little girl named Melody Quinn, who lives in an apartment nearby with her mother, may have witnessed the killings, but is so disturbed by the event that she can't remember much.
The story proceeds with Alex Delaware becoming increasingly drawn into investigating, and gradually uncovering, unsuspected major criminal activity, involving many perpetrators and victims.
A 1986 New York Times review said that, after a "properly taut start", "the solution to the mystery becomes apparent early on and that leaves the movie...tumbling rapidly into ever more unbelievable situations".
[1] Jeff Jarvis of People magazine called When the Bough Breaks "a nice, tight, tense little murder mystery" with "some neatly shocking scenes".