Jake and his pal Bud's journey begins six months after he is released on parole and is occasioned when his girlfriend Donna dumps him and aborts their child. After an aborted suicide attempt where the Norelco shaver cord he used to hang himself broke, on an impulse—the source of the title; everything in Jake's life happens "just like that"—he calls up Bud, who lives by the same credo, and the two take off with no particular destination in mind. They're just going "south"—somewhere where it's warm. An hour before they leave, Jake on another impulse, holds up a convenience store to get some traveling money.