Chicago February 14th 1929. Al Capone finally establishes himself as the city's boss of organised crime. In a north-side garage his hoods, dressed as policemen, surprise and mow down with machine-guns the key members of Bugs Moran's rival gang. The film traces the history of the incident, and the lives affected and in some cases ended by it.
| Writing | Howard Browne | Screenplay |
| Directing | Roger Corman | Director |
| Camera | Milton Krasner | Director of Photography |
| Production | Paul Rapp | Associate Producer |
| Sound | Fred Steiner | Music |
| Editing | William B. Murphy | Editor |
| Crew | Harvey Parry | Stunts |
| Production | Roger Corman | Producer |
| Visual Effects | L.B. Abbott | Visual Effects |
| Art | Walter M. Scott | Set Decoration |
| Writing | Monte Hellman | Dialogue |
| Sound | Herman Lewis | Sound |
| Crew | Dale Van Sickel | Stunts |
| Sound | Lionel Newman | Original Music Composer |
| Directing | Wesley Barry | Assistant Director |
| Production | David Silver | Unit Production Manager |
| Sound | David Dockendorf | Sound |
| Visual Effects | Emil Kosa Jr. | Visual Effects |
| Costume & Make-Up | Margaret Donovan | Hairstylist |
| Visual Effects | Art Cruickshank | Visual Effects |
| Sound | Urban Thielmann | Orchestrator |
| Costume & Make-Up | Ben Nye | Makeup Artist |
| Art | Philip M. Jefferies | Art Direction |
| Art | Jack Martin Smith | Art Direction |
