New York medical examiner Dr. Henry Morgan hides the secret of his immortality, even as he works to uncover its cause.

When the police deem a death Henry thinks to be a homicide a suicide, he and Jo investigate. Henry enlists Abe's help to track down his anonymous caller.

Multiple deaths are caused by a highly sought-after product called Aterna that claims to reverse the aging process; Abe is tempted to try Aterna, despite the dangers.

When the matriarch of one of New York's wealthiest families dies, the family demands answers. Also, memories brought on by the case torment Henry.

Henry casts an eye over the death of a reformed addict, before spinning a tall tale when Jo asks questions about his friendship with Abe.

Henry receives a tip-off from his mysterious caller while trying to solve the complicated case of a copycat killer.