Myshko and Lev are fellow villagers. Due to different reasons, they are aboard a Ukrainian Navy ship U311 "Cherkasy" stationed at the port of the Donuzlav Bay in the Crimea. While the crew of the minesweeper "Cherkasy" conducting military training and naval exercises, the Ukrainian president Viktor Yanukovych flees the country and the Crimea is occupied by the "little green men". The ship is returning to its base but the port is already lost. "Cherkasy" and several Ukrainian ships are blocked in the Donuzlav Bay by Russian army. Ukrainian ships surrender in single file and only the "Cherkasy" crew resists and keeps fighting a brave yet desperate struggle against the enemy.