About a heroic episode in the activities of an underground Bolshevik organization in 1912.
Vera (Tamara Alyoshina), an experienced conspirator, who escaped exile, arrives at the Sevastopol organization with a party mission to obtain weapons. The underground group "Swallow", with which she comes into contact, enters a dangerous unique fight with an experienced dangerous enemy, the secret police officer Yarnovsky (Vladimir Druzhnikov), and despite the difficulties and many obstacles, fulfills the mission party.