Holmes discovers that a man who died of a heart-attack was indeed murdered. This leads Holmes and Watson to discover that the hospital has an "Angel of Death" that is killing those in pain and on the track to death. Sherlock uncovers that it was the janitor, a former doctor in the Ukraine. Holmes then exposes the hospitals best surgeon by figuring out that he too knew of that someone was mercifully killing patients. The doctor set up his patient so she would be killed by the Angel of Death to cover his tracks for screwing up her surgery. Meanwhile, Joan runs into an old friend where she thinks that one of Carrie's patients needs to be tested for a heart condition; she was right and saved the patients life.