Schoolboy Mitya is in desperate need of money to repay a debt, but his father angrily denies him assistance. Dejected, under the instigation of a friend Makhin, Mitya simply changes a 2.50 note to read 12.50, but this one evil deed sets off a chain of events that affects the lives of dozens of others, when his one falsehood indirectly causes a man to murder a woman.