Postern of Fate is a 1973 novel by Agatha Christie. It is the final novel written by Christie.

The story is about Tommy and Tuppence, who are in their seventies. They move to a quiet English village for retirement. They soon discover that their house holds secrets.

An ominous message about a 60-year-old murder sets them to investigating threats to British security. They decide to investigate just for the fun of it. Then their gardener is murdered and someone fires a gun at Tuppence.

At the end of the novel, the couple are congratulated by appreciative government officials.

Postern of Fate is considered less tightly plotted than the previous Beresford novels. It is probably the most-disregarded book in Dame Agatha's oeuvre.