Obsessed with the construction of Melbourne's new West Gate Bridge, where his father works, Ray Johnston overhears a conversation about a fault in the bridge and a plan to loosen its bolts. He tells his best friend Tom and confides in his father, who insists that he keeps quiet about it.

Ray is devastated when he hears sirens coming from the worksite. He races there to find that the bridge has fallen, taking several workers with it. Is his dad one of them? What else can he do?