A young doctor is coerced into assisting an older doctor with a complex operation conducted under a new form of anesthesia, called "Sacral Anesthesia." The patient, a prominent citizen in the community, dies under mysterious circumstances during the operation. The young doctor is haunted by the death and, despite attempts to discourage further investigation, he persuades the coroner to allow him to take fluid from the anesthesia site. The fluid contains cyanideso the death precipitates a murder investigation. The seven immediate suspects include all five members of the operating room team. Immediately after announcing his finding, the doctor himself is poisoned and barely survives. Another death from cyanide occurs before the mystery is finally solved.