Captain Nagornov’s tactic aboard the Magnitogorsk is to sneak up on the corvette underwater. To do so, he needs to determine the exact location of his enemy, without giving away his own. Meanwhile, captain Slonov’s corvette is preparing a surprise for its enemy – the marines in armoured vehicles are ready to be deployed in the water. But, as the military exercise commences, the two teams notice the presence of a third party: a mysterious aircraft that seems to have its own agenda in this competition.