Night. Hospital. Resuscitation.Patient Yablochkov, who was already on the mend, suddenly suddenly has a cardiac arrest. The duty doctor Agapov and two orderlies unsuccessfully try to revive the unfortunate man. Adrenaline, ventilator, defibrillator - all to no avail. It is very strange that the monitor with the sound alert was not connected to Yablochkov, although Agapov personally connected the electrodes to the patient. No less strange is the fact that the experienced nurse Angela fell asleep at her post, which had never happened to her before. Senior Lieutenant Vorontsov from the Investigative Committee believes that this was not an ordinary case from medical practice, but a carefully thought-out murder. And it was committed by the mistress of the deceased, citizen Lyuba Yasnova, having entered into a secret conspiracy with doctors. And now all the doctors who were on duty on that fateful night fall under suspicion. Doctor Agapov is facing a real sentence. But, fortunately, fate unexpectedly brings him together with private detective Arseny Stroganov...