A group of children on holiday in Malta join an aqua-lung diving class. One of them discovers a wreck, and disobeying instructions decides to investigate on his own, with near serious consequences.

Lt Commander Matthews is spending a holiday in Malta to teach his son Derek aqua-lung diving. Other children including the objectionable Spike join them. Against all warnings Spike goes off on his own breaking all the rules laid down and although he discovers a wreck and finds a few coins he almost loses his life but Derek saves him and Spike becomes a changed boy.—tonyman