This is a great film to add to your collection of mysteries. It is up there with Christy and Sayers. All the elements are there and blend well.
The actors are well chosen to match the characters and the acting is bang on. The sets were perfect and not distracting from the story.
There are several approaches one can take while telling a story. One is like Tony Hillerman who usually has two parallel stories that have characters periodically crossing each other and may not converge in the end. The other is the worlds within worlds approach as with the book "Sophie's World" or the film "The Thirtieth Floor" (1999). This story was more standard mystery with the usual suspects that all could be guilty. All the clues are there and the butler does not come out of the closet just before the end. Yet in the end, we get not one twist but a series of plausible twists. Leave it to a Mathematician.
In the film we get a statement "I believe in Pi" this give away the armatureness of the math section of the film as everyone in industry knows the ' Pi (~.7854816) is the formula to convert form one geometric figure to another look it up. You do not need a calculator if you remember 7854 in your head.
The story starts with a famous woman being murdered, no doubt, about it, two people find the body and a mysterious mathematical clue points to possible future murders. Can the clues be deciphered using a mathematically attitude and future murders prevented; or will we have to rely on good old-fashioned detective skills?
Be sure to watch again to see what clues you may have missed.