December 1942. Wearing a German uniform, a former Red Army soldier, Sergeant Alexander Ivanovich Lazarev (Vladimir Zamanskiy), voluntarily gives himself up to the Soviet partisans. However, knowing that he had previously defected to the Germans, Commander Lokotkov (Rolan Bykov) and Commissar Petushkov (Anatoliy Solonitsyn) decide to give Lazarev a chance to clear his name, putting his loyalty to the test through a series of operations in Mother Russia's dangerous, snow-covered roads. In the end, is Lazarev a traitor or a patriot?