** SPOILERS **
The most bizarre yet delightful surprise about John Carter, for one who has never had interest in reading the novels by Edgar Rice Burroughs and knew next to nothing about these stories but does love television programs on HBO, is that in the movie, Mars is in the grip of a civil war between the cast of Rome and McNulty from The Wire. The two main Martian cities are helpfully color coded to tell good from evil. The good blue side is led by Ciaran Hinds and James Purefoy, both essentially playing Martian versions of Gaius Julius Caesar and Mark Antony. Opposing them in evil red is Dominic West, in another iteration of the grimacing villains he plays in movies. He was pretty much an identical heavy in 300. West doesn't have Bunk, Lester, Kima, or Herc from Baltimore with him, but Polly Walker from Rome jumped loyalties and is on West's side. You just can't trust Atia of the Julii.
If John Carter had just stayed focused on these HBO series actors, that would have been terrific. Alas, John Carter has to be about John Carter. Standing with good HBO against evil HBO is Tim Riggins from Friday Night Lights. Riggins - sorry, Taylor Kitsch - is an ornery young civil war captain who gets teleported to Mars by a mysterious blue light. The power of the blue light, which can provide trans-world teleportation or be used to shoot lightning from your hands, is coveted on Mars. John Carter discovers that on Mars, Earthlings are stronger and can leap miles into the air like the Incredible Hulk (but are no more intelligent, notes Mark Strong, an evil ghost-like servant of some ill-defined goddess, pulling the strings to keep Mars at war). Also, Mars isn't called Mars on Mars. It's called Barsoom, and the Martians - sorry, Barsoomians - have their own names for all the planets in our solar system that have nothing to do with Greek or Roman gods once worshipped on Earth.
Stripped down to a rags and tatters He-Man look, John Carter is knocked around a lot and endures pile-ons by every Martian he meets, be they humanoid "red people" or the 12 foot tall green praying mantis-looking barbarians he ends up spending most of his time with. They even give him an ugly, slobbering, but loyal Martian dog that runs with super speed. Carter befriends their leader, Tars Tarkas, voiced by Willem Dafoe, who ends up overthrown and imprisoned to fight in an Attack of the Clones-like gladiator arena with John Carter for being his friend. I confess I could not learn any of the other Martian names. Normally, I'm good at this stuff, but it all sounded like gibberish. Nor could I tell exactly what everyone was talking about and what it was in particular they wanted.
What the main Martian girl in the movie, Lynn Collins, doesn't want is to marry the evil West to bring "peace" to Barsoom. Collins plays A Princess of Mars, who's also some kind of Martian super scientist and more prone to spouting pseudo-scientific gibberish than the other Martians. She's pretty buff, but frankly, she's a bit of a pill. John Carter falls in love with her, of course. The movie doesn't give him any other options for women who aren't green monsters. This is in the Star Wars tradition. John Carter finally decides going back to his "cave full of gold" on Earth is less important to him than fighting for Barsoom. Thus he leads a rebellion to stop a royal wedding, just like when Flash led the Hawkmen to stop Dale Arden from marrying Ming the Merciless in Flash Gordon.
It should be noted the "John Carter of Mars" books are the pulpy predecessors of just about every space opera tale of the 20th century, but it did John Carter no favors to arrive long after the movies it inspired have made indelible impressions on pop culture. As John Carter, Kitsch is gung ho yet seems out of his depth as a classic pulp adventure hero. Still, he means well. Gazing across the dusty, windswept vista of Mars, it's at first unclear if John Carter really wants to stay or leave. In the end, as he must, John Carter of Mars chooses Barsoom forever.