This specific Poirot story is an based on a play that Christie wrote in the 1920s, apparently as a response to a less successful stage adaptation of Poirot. 
Osborne, who wrote it did a very good job adapting the script and giving it the feel as if Christie had written the entire thing herself. However there are definitely moments where it becomes pretty clear that this was indeed based on a play. Nothing that takes you out of the story, id say, just some details pointed out a little extra and it is very clear whenever someone enters a room.

Overall a fun classic whodunnit with a good handful of twists to keep you readig