Dennis Lehane is an American author. He has published more than a dozen novels; the first several were a series of mysteries featuring recurring characters, including A Drink Before the War. Four of his novels have been adapted into films of the same names: Clint Eastwood's Mystic River (2003), Martin Scorsese's Shutter Island (2010), and Gone Baby Gone (2007) and Live by Night (2016), both directed by Ben Affleck. His short story "Animal Rescue" was also adapted into the film The Drop, noted for being the final film role for actor James Gandolfini.

Mystic River is a 2003 American neo-noir crime drama film directed and co-produced by Clint Eastwood, and starring Sean Penn, Tim Robbins, Kevin Bacon, Laurence Fishburne, Marcia Gay Harden, and Laura Linney. The screenplay, written by Brian Helgeland, was based on the 2001 novel of the same name by Dennis Lehane. It is the first film in which Eastwood was credited as composer of the score.