Hercule Poirot appears very little in this novel, and that is mostly near the end of the story. In spite of this, Three Act Tragedy is a highly entertaining mystery.
Thirteen are gathered for dinner (plus one) at the home of famous actor Sir Charles Cartwright. We learn all about the various attendees from an omniscient narrator and somewhat from the observations of Mr. Satterthwaite, a fellow who is a patron of the arts and who considers himself a keen observer of human nature.
Practically before the dinner party has a chance to get started, one of the guests, a clergyman, suddenly seems to choke on his cocktail, and in moments he's dead.
A doctor on the scene, Bartholomew Strange, pronounces Stephen Babbington dead. Babbington had a few health problems, so it is assumed one of those took the elderly man at this misopportune moment.
Charles Cartwright, however thinks something more happened, and he discusses this theory with his friends Satterthwaite and Strange. He also mentions his theory to young Hermione "Egg" Lytton Gore, who has a bit of hero worship for the older Charles.
A few months later, there's another dinner party, with many of the same attendees, sans Poirot. Another death immediately after a drink is taken.
Now the game is on, with Satterthwaite, Cartwright and Egg consulting and crisscrossing the countryside to try to find out who the murderer is, for they're all certain now there were two murders.
The first murder, of the innocent seeming clergyman must hold the key. What could be the motive, and why was there no trace of poison in the glasses used by either victim?
I wondered at the point of view and the leaving Poirot out of the hunt for the killer for much of the story. The would be detectives have a thrilling time out asking questions of witnesses. Was this to give the reader a viewpoint wherein they knew what the detectives knew, and they could solve the murder right along side them? Poirot himself famously holds much information back.
I, for once, actually suspected the killer, but not their motive or method. I was a bit proud of myself.
Three Act Tragedy was formerly published as Murder In Three Acts which is a better title, all in all, I think.
