Robinson was pretty sure to come along sooner or later. Then what will happen? The avenger arrives. He knows the name, he knows the address. He strikes! All is over, vengeance is satisfied, and Miss Elsa Hardt has escaped by the skin of her teeth once more. By the way, Hastings, you must present me to the real Mrs. Robinson⁠—that delightful and truthful creature! What will they think when they find their flat has been broken into! We must hurry back. Ah, that sounds like Japp and his friends arriving.”

A mighty tattoo sounded on the knocker.

“How did you know this address?” I asked as I followed Poirot out into the hall. “Oh, of course, you had the first Mrs. Robinson followed when she left the other flat.”

“ A la bonne heure , Hastings. You use your grey cells at last. Now for a little surprise for Japp.”