Boston private investigators Patrick Kenzie and Angela Gennaro's relationship has hit the skids - their long-standing professional commitment and growing romance have disintegrated due to seemingly irreparable personal differences. But despite these problems, Prayers for Rain brings them together again to close down a predator whose modus operandi seems to put him beyond the law. This killer's insidious murder weapon is within his victims' minds: no smoking gun, no bloody knife, just merciless manipulation until despair drives his targets to kill themselves.

As Patrick and Angie attempt to identify and save his next victim, this sinister force turns on them and thus begins a dangerous battle of wits: a tormenting, life-threatening game of psychological warfare in which simple survival seems a mixed blessing - because not even the winner will emerge unscathed.