Adapted for the screen by Kevin Brodbin and Frank Capello from the comic book Hellblazer by Jamie Delano and Garth Ennis, Constantine is sort of like Men in Black, only without any of the fun. In Men in Black, Will Smith and Tommy Lee Jones spot creatures from other worlds walking around in the human skin of earthlings. Then they kill them, and along the way we laugh reasonably often.
In Constantine, our title character, John Constantine (Keanu Reeves), also spots creatures from other worlds walking around in the human skin of earthlings. Following tradition, he also kills them, or some of them, anyway. Only the creatures he spots and sometimes kills aren't from Out There but rather from Down There. From hell. They are demi-demons who have been sent to Earth by Satan to try to seduce us mortals into sin so they can later claim our souls. Why don't you bet the rent on that long-shot nag? Don't worry that it's never won a race; it will this time. Hey, I bet you can't chug that bottle of vodka. Go ahead; I dare you.
Of course, the God of this movie universe demands a level playing field. So sometimes Constantine spots demi-angels here to offer more beneficent suggestions. Save for your children's college educations. Have you thought of helping that blind lady across this busy intersection? Constantine doesn't kill the demi-angels he spots, although there's one pestiferous demi-angel named Gabriel (Tilda Swinton) that he'd like to kill. And that makes just about as much sense as everything else in this picture.
The following details are required for our plot: Constantine has been smoking since he was 15, and he is dying of lung cancer. We're told he smokes a pack and a half a day. But he appears to smoke a pack and a half an hour. As a teen, Constantine tried to commit suicide. His heart stopped for two minutes, during which time he was dead and in hell. So now he's damned, and he's hoping to send enough demi-demons back to the fiery underworld to earn a free pass to heaven before he coughs his last.
In his demi-demon demolishing, Constantine is assisted by three men he treats with equal disregard. Chas Chandler (Shia LaBeouf) is his driver and Robin-wannabe. Father Hennessy (Pruitt Taylor Vince) is an exorcist unusually skilled at rolling his eyeballs backwards into his skull. And Beeman (Max Baker) is Constantine's Q. He outfits our hero with the kinds of weapons a demi-demon destroyer demands: the bullet that shot Pope John Paul II, holy water from the River Jordan and a box of screech beetles (demi-demons think their cricketing sounds like fingernails on a chalkboard). We wait with delicious anticipation (OK, we wait with yawning expectation) for Constantine to employ each of his weapons at some particularly perilous moment. But after a while we realize that we aren't watching something conventionally coherent and give that idea up. Constantine's three assistants also serve our plot by providing required cannon fodder. They weren't actually created to contribute. They were designed from the get-go as Dead Meat.
Our plot involves the suicide of Isabel Dodson (Rachel Weisz), the investigation of her death by her twin sister, Angela (yes, Rachel Weisz), and Angela's enlistment of Constantine to go down to hell to see if Isabel is there. Constantine has racked up a ton of frequent flyer miles on the Earth-to-hell route. Sometimes he goes there by staring into the eyes of a cat while immersing his feet in a pan of water. But sometimes he has to visit his friend Midnite (Djimon Hounsou) and endure some jolts from the Sing Sing electric chair that Midnite keeps in a store room for reasons never revealed. Very little comes of this plot, so now that you know the bare essentials, you can safely forget about it entirely. There's also something about the power of the sword that killed Jesus. But it's not important. Every once in a while, Constantine edges into areas of theological contemplation that threaten to prove interesting. The movie's premise is a Job-like world where God and Satan contend for souls as a game of sport. This leaves Constantine, who knows the rules of the game better than anyone else, both craving his creator's blessing and contemptuous of a diety who would treat the human race as we might an ant farm. The movie suggests that Constantine will need to be capable of self-sacrifice to achieve the salvation he seeks. But even in this it errs for those who believe that "not by works but by faith are you saved."