(Photo: Getty Images) 
Kenneth Branagh has turned his attention to Agatha Christie’s work, adapting Murder on the Orient Express (2017) and Death on the Nile (2022) for the big screen.
He directed and starred in both movies, taking on the titular role of Belgian detective Hercule Poirot. There are now plans for a third movie, reports ComingSoon.net.
The script is already finished, written by Michael Green, who wrote the screenplays for the aforementioned adaptations. Branagh will be returning for the third installment, set to direct and star once again. The storyline hasn't been announced, but 20th Century Studios president Steve Asbell dropped a hint when talking to The Hollywood Reporter, saying viewers can look for one of Christie’s “lesser-known novels.”
Asbell shared his excitement about the upcoming project, saying, “We have the Poirot franchise, we have other Christie stories. I love these films, I love Ken. We have a third script written, by Michael Green, that is a pretty daring shift in genre and in tone. It’s post-war Venice and an adaptation of one of the lesser-known novels. So, I think you’ll see the mustache again.”
Speaking of Branagh’s unique mustache, here’s a peek at him in the two earlier movies:

According to History.com, Christie’s beloved Poirot appears in over 25 novels. It's not clear which novel will be adapted next, but there is a lot of material to work with. 
The next movie is a mystery. Do you want to try and solve it with a guess?