Never a Second to Myself (2010)

Returning from a high profile mission, Mark--a contract hitman, delivers a body to his contact at a discreet warehouse location. Upon delivery, Mark's contact explains his performance was too sloppy, and that the executive in charge of hiring has decided not to pay for his services. Frustrated, Mark decides to kill the contact. While disposing of both bodies, a passerby accidentally stumbles onto the scene, forcing Mark to dispose of a third body. Soon, someone else arrives - and it gets worse. Much worse.