Primary Suspect (2000)

While on an undercover infiltration mission, Denver police detective Christian Box has to use some drugs, and is believed by many to have become an addict. It goes wrong, and his wife, also in the operation, is killed. He gets the blame, but thanks to Lieutenant Blake he isn't officially charged, "just" reduced to desk work. Two years later, he grabs a unique opportunity to mount a new, dodgy undercover operation which should constitute his revenge against the crime family.