The full music video for "Bad" is an 18-minute short film written by novelist and screenwriter Richard Price, directed by Martin Scorsese and starring Michael Jackson. Jackson portrays a boy named Daryl who has just completed a successful term at an expensive private school. He returns to the city by subway, arriving in a derelict neighborhood.

Daryl arrives to find his house empty (his mother is played by Roberta Flack, albeit in voiceover), but is greeted by his old friends, led by Mini Max (an emerging Wesley Snipes) and spends an evening with them. At first relations are friendly, if slightly awkward, but the situation deteriorates once the rest of the gang realize how much Daryl has changed, and in particular how uncomfortable he has become with their tendencies towards petty crime. In an attempt to show his friends he is still "bad", Daryl takes the gang to a subway station (The Hoyt Schermerhorn Station in Brooklyn) where he attempts to mug an elderly man but bottles out at the last minute. Mini Max berates Daryl and tells him that he's no longer bad.

After more abuse from Mini Max, the video jumps from black and white to color and Daryl, now dressed head to foot in leather and joined by a crowd of dancing punks, sings "Bad" (it is at this point that the edited video generally begins when played on television). His insistence that Max is headed for a fall are nearly Daryl's undoing, but eventually his friend accepts that "that's the way it goes down", and, after a final handshake, heads off leaving Daryl. The scene shifts back to black and white as Daryl, alone and back in his tracksuit, watches them leave.

Text quoted from: http://en.wikipedia.org/wiki/Bad_(Michael_Jackson_song)