It is the mid 1960's - the crew of HMS ORCA are off again. Scruffy and bearded; their lives on board the submarine are cramped, claustrophobic, damp, dirty and they smell continuously of diesel. Food and the odd movie are their only distractions. Yet they relish their "pirate image" and are intensely proud of being submariners. Their "routine" running period turns into an action packed adventure full of hairy incidents, fun, and the odd frolic. Setting sail from Portsmouth they jump in at the deep end, their adrenalin pumping, and the action starting from the off.