Watch Fire Line (1961) Official Trailer

Two young crooks who scam betters in the race track are employed by a yakuza gang called the Shigemori Syndicate to steal a shipment of handguns from a rival gang. Somewhere in the process they find themselves on the run from their own gang and one of them becomes himself romantically entangled with the boss's girlfriend. An ambitious underboss of the gang offers them a way out if they murder the previous boss but things don't turn out as planned (for everyone).