en Cuevana 3. The American submarine is rushing to the intended target, from where the U.S. ballistic missiles are shot. For the third month the boat has been on a cruise, everyone is tired of this life, the captain is nervous - the speed is at the limit of the machine's capabilities. Only the chief mate, the only person on the boat who will not hesitate to press the fatal button, feels confident ... When the target is only minutes away, the radio operator raises the alarm: the Moscow radio announces that an important government message is about to be announced. The base is silent. Fearing that war has broken out, the captain declares combat readiness, but at the same time Moscow radio reports the launch of the world's first cosmonaut.