Malcolm Hughes Colin Friels is a gifted, autistic tram enthusiast and a mechanical genius whose modest inner-city cottage overflows with remarkable gadgets. When his boss discovers that Malcolm built a cut-down tram during work hours using company materials, he is fired. With his mother dead and no income, a local shop owner suggests taking in a border, Frank Baker John Hargreaves. Frank's brassy girlfriend Judith Lindy Davies soon moves in, and Frank reveals he's a petty criminal who has recently been released from prison. Despite their differences, the trio form an awkward friendship.
Malcolm's inventive brain quickly becomes the trio's engine. In his first demonstration, he shows Frank the getaway car that splits into two independently powered halves, and they use it to escape after Frank steals cash from a bank customer. For the next demonstration, Malcolm stages a near-miss payroll delivery heist using a radio-controlled model car with a video camera, a speaker, and a gun loaded with blanks to threaten the guards. Frank interrupts the scene, joins in, and helps steal the cash, though the loot is lost when the planned getaway route through a street drain is too tight.
The group then devises an audacious plot to steal the weekly cash delivery from a major bank, about $250,000. Malcolm collaborates with Frank and Judith to craft a set of ingenious inventions. They plant armed, remote-controlled motorised robot rubbish bins inside the bank, positioning them on an overhead walkway between two buildings. When the guards carry the cash on a trolley across the walkway, the robot bins stop them. A Ford Transit below has a spring-loaded arm that swings up, shatters the walkway glass, and pushes the cash through a roof chute into the van. The trio then disappear, disguising the van as an ice-cream truck. They also release a Ned Kelly-like dummy in a radio-controlled wheelchair armed with two shotguns as a decoy for the police. They manage to elude pursuit, but two cops encounter them at an ice-cream stop. Frank speeds away, and the group switches to a backup plan: they abandon the van and flee on foot; moments later, the police sweep the area and see only the back of a tram pulling away. In a final twist, the front of the tram is revealed to be Malcolm's custom mini-tram, carrying the trio and their loot aboard.
The film closes with Frank leaving a bank in Lisbon, Portugal—another city known for its tram network—where he has just deposited the Melbourne heist’s proceeds. He meets up with Malcolm and Judith at a cafe, and they begin laying plans for another daring crime.
