Sadie (The Secret Adversary)

In the novel The Secret Adversary, Sadie is a person named on a list of survivors of the Lusitania. Tommy and Tuppence were searching for a woman whose Christian name was "Rita", believing that this Rita might be a witness to what happened between Danvers and Jane Finn on the ship. However, as the list of survivors mostly listed people as Mrs. or Miss, they had to call on the survivors individually to find out their Christian names. Sadie was one of the people they visited.

Sadie is described as being a "vivacious American lady". When Tommy and Tuppence call on her, she gives them a long lecture on universal suffrage.