The servant Cajthaml comments with humor and affection on both the routine and dramatic events of one day in a hospital where staff are carrying out complicated heart operations. At six o'clock in the morning Cajthaml winds up the tower clock and senior sister Pesková goes off to make her first inspection of the operating theatre. Today they will be operating on the waiter Horácek, whose heart has more or less packed up. The operating team, led by the senior consultant Hruza, is made up of highly responsible experts, but each of them has his or her own personal problems and cares.