I have seen a lot of filmed murder mysteries from drama to slapstick: 
Thin Man series, 
China Town, 
Minority Report, 
The Usual Suspects, 
The Maltese Falcon, 
Who Framed Roger Rabbit, Clue, Rear Window, Scoop, Murder by Death, even the occasional 
Dr Who and the TV shows 
Columbo, 
Grimm and Perry Mason. There’s something truly satisfying about solving a puzzle with the end result the protecting of the innocent and the meting out of justice. But my favorite has always been Murder on the Orient Express. A group of strangers stuck on a snow bound train with a murdered man and a famous detective and one of them a murderer. A bit like Christie's Ten Little Indians but, to me, Orient Express has more pinache.
I’ve seen the 1974 version many times. Knowing the ending does nothing to undermine the enjoyment of watching the mystery unfold like a beautifully formed rose bud – all the parts slowly falling into place. Who wouldn’t like it?! With the star studded cast including the likes of 
Albert (Bourne franchise) Finney, 
Sean (James Bond) Connery, 
Lauren (Humphrey Bogart’s wife) Bacall, Ingrid (Casablanca) Bergman, SIR John Gielgud, Anthony (Psycho) Perkins. The list goes on – it is a BIG cast. 
But as good as the 1974 version was, it is only the amusing movie hors d’oeuvre to the cinematic banquet that is 
Kenneth Branagh’s 2017 Murder on the Orient Express. Not only is this the best rendition of a murder mystery I have ever seen, it is one of those rarest of birds – a perfect movie. Branagh brings brilliance to anything he undertakes – from 
Thor to 
Cinderella to 
Hamlet* (ALL of which he directed). He is one of those auteurs, like Orson Welles and Woody Allen who can both star and direct in the same movie and create masterpieces.
Prudence, by defintiion, is the virtue of knowing the right thing to do at any given time. When you are someone who sees the subtle imperfections of the world this virtue becomes an obsession. In a detective this can be a superpower…and a curse. Such is the struggle of Branagh's Hercule Poirot. 
This kind of complex personality overlay onto an already brilliant screenplay is an example of what makes Branagh's Murder on the Orient Express special. It could have been refilmed as another lovely remake with modern celebrities. The last theatrical version was in 1974, as I have said, so it is due for a remake. But true to his genius and his respect for his audience, Branagh is not content with merely revamping an already rich treasure of a story but like Gershwin's ability to create a timeless song from a simple catchy line of music, Branagh takes a classically fun tale and reworks it into a presentation worthy of a Shakespearean telling.
As in the original, the premise is that a murder takes place on a train, which locomotive is almost immediately and Providentially caught in an avalanche of snow. The manager of the train, a good friend of Poirot's, implores Poirot to solve the mystery for him before the train is freed and the killer has an opportunity to escape. As well as catching a killer, he also (by the way) wishes to avoid the shame of scandal to the Orient Express from an unresolved atrocity committed aboard this regal moving institution.
Of all the movies I have ever reviewed this is the one about which I would be most loathe to commit a spoiler ……. so will not.
But I will say there are a few minor tweaks to the story, re-imagined by Michael Green from, obviously, the Agatha Chtistie novel of the same name. These changes work well, and add depth of character and intrigue to even Christie's fascinating creation. 
One such contribution is Branagh's Poirot which, while I will not go into detail, is a brilliantly satisfying choice which makes the usually taciturn and ascerbic character more approachable and likeable, aware of his own shortcomings and has a character arc which dovetails beautifully with the theme and complexities of the story.
If you have not read the book or seen the 1974 movie, which by the way is very good, and are then fortunate enough to be able to see this 2017 version with virgin eyes, do NOT watch any trailers, see any interviews, read any opinions but go straight to the movie with childlike delight. If you ARE familiar with the story then go to revel in the brilliant directing. 
Branagh stages the film like a fairy tale with all the exotic detail that was Stamboul (Old Istanbul) in 1934 and the extreme elegance of the Orient Express which in its day was host to Princesses and Counts. The colors are bright, the costumes splendid reflections of the complex suspects. And enjoy the sheer artistry of Branagh direction as he shoots with elegance equal to the time and place. 
He uses mirrors, windows and framing to fracture images hinting at characterizations; overhead shots to both reveal and hide clues at the same time. Dramatic events are bold and large as life; intimate scenes feel almost intrusive into private tensions and personal conflicts. 
At turns I laughed out loud and was brought to tears.
And Branagh knows how to work an ensemble cast. From the musical rendition of Shakespeare's 
Love's Labours Lost to the light comedy 
A Midwinter's Tale to 
Hamlet with its massive star studded cast, he knows when to shine and when to hold back and always gives every member of his cast ample opportunity to be memorably in the forefront.
Every one of the actors does a superlative job. 
Not suprising as any director who could inspire a good Shakesepearean performance out of Keanu Reeves in Much Ado About Nothing could get a good perfromance out of even a dust mop. But most of these guys do not need such inspiration as they are already accomplished actors.
It is my honor and delight to mention each of the main performers:
Kenneth Branagh, director and lead, plays Poirot himself. I have seen enough Branagh to know that if he thought someone else could have done a better job he would have hired him. I'll tell you this is the best Poirot or classic detective of this genre I have seen anywhere.
Johnny (Jack Sparrow) Depp plays Edward Ratchett, American gangster and suspicious ne'er-do-well who brings a frightening intensity to what otherwise could have been a cookie cutter stereotype.
Sir Derek Jacobi – friend and collaborator of Branagh in a number of previous outings from the aforementioned
Hamlet to Henry V to Cinderella, plays Edward Henry Masterman, British manservant to Ratchett. Jacobi is a knighted Shakespearean thespian who lends a graceful sympathy to Masterman.
Josh (Beauty and the Beast) Gad plays Hector MacQueen, Ratchett's assistant, lends a surprisingly effective though odd combination of Bogart and Peter Lorre from Casablanca into this character of questionable motives.
Daisy (Rey from Star Wars) Ridley plays Mary Debenham, stepping away from her interstellar Jedi to bring a singular classy elegance to her role as governess.
Leslie Odom portrays Dr. Arbuthnot, a man of many surprsing talents with skill and credibility.
Dame Judy Densch – M, Shakespearean actress of tremendous dignity and comportment – continues to demonstrate her command of her art in even one of the smaller roles as the elderly Princess Dragomiroff.
Willem Dafoe (Green Goblin from Spiderman, Platoon, Odd Thomas, voice of Gill in Finding Nemo) equally at home in comedy or drama, as villain or hero, brings his many talents to bare for the German professor Gerhard Hardman.
Olivia Coleman is solid as Princess Dragomiroff's personal maid.
Manuel Garcia (Magnificent 7) Rulfo is charming as Biniamino Marquez the Italian born newly Americanized citizen car salesman.
Marwan Kenzari is Pierre Michel, the ubiquitous conductor.
Michele Pfeiffer redeems herself from her awful participation in the terrible Mother! as the wealthy manhunting widow, commanding and entertaining in every scene she's in.
Luc Boynton portrays the fragile ephermeal Countess.
Sergei Polunin is almost comic relief in his intensity as the tightly wound Count, protective and attentive husband of the Countess.
Tom Bateman plays Bouc, playboy, friend of Poirot and ultimately responsible representative of the owners of the Express with style and contagious enthusiasm.
Penelope (Pirates of the Caribbean, Nine) Cruz, in a surprising turn plays Pilar Estravados, the intense missionary with an unexpected tough streak.
So go see this masterpiece of film making. Whether you have never heard of Agatha Christie before or if you've got the story memorized from a previously favorite version, you will more than be rewarded for your time in viewing this crown jewel retelling of the ultimate murder mystery.
* Branagh's Hamlet is the most spectacularly filmed Hamlet ever to grace the screen and the ONLY filmed theatrical unabridged Hamlet so far in existence.