One Good Turn.

Matt, a home arcade games programmer runs into an old acquaintance who saved his life years earlier from a burning automobile. The rescuer, Simon, is down on his luck, living like a bum. The grateful Matt feels obligated to help Simon, so he takes him into his home and gets him a job in the mail room of his company. However, what Matt doesn't know is it was no accident running into Simon, and Simon has an old score to settle with Matt, going all the way back to the night Simon saved Matt's life.