The Long Kiss Goodnight.

Samantha Caine is a small-town schoolteacher and mom with no memory of her life before washing up on a beach eight years ago. After a car accident and a violent home invasion trigger flashes of her past, she discovers she used to be a deadly CIA assassin. Teaming up with a wisecracking private investigator, Samantha must return to her old ways to take down the people who tried to erase her.