In the Mexican countryside, a scavenger named Manuel finds a spearhead wrapped in a Nazi flag at the ruins of an old church, which is later revealed as the Spear of Destiny. Manuel becomes possessed and travels to the United States. John Constantine (Keanu Reeves) exorcises a Filipina girl possessed by a demon trying to break through to Earth, which should not be possible under the wager's rules. He meets with the androgynous half-angel being Gabriel (Tilda Swinton). He asks Gabriel for a reprieve from his impending death from lung cancer brought forth by prolonged smoking. Gabriel declines, telling Constantine that he exorcises demons for selfish reasons and can not buy his way into Heaven. After being assaulted by another demon, Constantine goes to Papa Midnite (Djimon Hounsou), a reputed witch-doctor who runs a club serving as neutral ground where half-breeds do not have to conceal themselves. Midnite does not believe Constantine's claim of demons crossing over. Constantine leaves, after exchanging hostile words with half-demon Balthazar (Gavin Rossdale). Elsewhere, a woman named Isabel Dodson (Rachel Weisz) commits suicide in a psychiatric hospital. Her twin sister, Detective Angela Dodson (Rachel Weisz), refuses to believe that Isabel, a devout Roman Catholic, would kill herself. Watching security footage of Isabel's suicide, Angela hears her say Constantine's name. Angela finds Constantine and asks him to help investigate. After they are attacked by winged demons, which Constantine believes were targeting Angela, he agrees to help...
Rotten Tomatoes consensus states: "Despite solid production values and an intriguing premise, Constantine lacks the focus of another spiritual shoot-em-up, The Matrix."Richard Corliss of Time magazine called it "a one-of-a-kind hybrid: a theological noir action film". In crediting the actors, he specifically cited Keanu Reeves' ability to "retain his charisma in [a] weird-silly moment" in addition to the performances of Tilda Swinton whom he referred to as "immaculately decadent". He also praised Francis Lawrence's usage of a significant number of camera locations and angles. He was, however, critical of the movie's climax, referring to it as "irrevocably goofy". Ella Taylor of LA Weekly wrote, "Constantine, which opts in the end for what I can only describe as a kind of supernatural humanism, is not without its spiritual satisfactions." Carina Chocano of the Los Angeles Times wrote, "Keanu Reeves has no peer when it comes to playing these sort of messianic roles-he infuses them with a Zen blankness and serenity that somehow gets him through even the unlikeliest scenes with a quiet, unassuming dignity." Pete Vonder Haar of Film Threat gave the film three stars out of five, stating that "the film (barely) succeeds, thanks to impressive visuals, the idea of an uncaring God wagering with Satan for souls, and two immensely enjoyable scenes (one with Weisz, one with Stormare) in which Reeves actually plays his character as the cynical asshole he really is." Jack Matthews of the New York Daily News gave the film a 2.5 out of 5, stating, "For all its spiritual angst, Constantine is about as silly as fantasies get." Michael Sragow of The Baltimore Sun also gave the film a 2 out of 5, stating, "It all comes off as a case of filmmakers wanting to have their communion wafer and eat it, too." Desson Thomson, a writer for The Washington Post, had similar sentiments of the film, specifically panning the film's distancing from the comic book upon which it is based: If you are a fan of the Hellblazer comic book series, on which this movie is based, you'll definitely need a distraction. The relation between Constantine and its source material is, at best, superfluous. The disparity starts with the original John Constantine (Reeves's character) being from Liverpool, England. Reeves from the city of John and Paul? As if. Leonard Maltin's annual publication Movie Guide gives the film a BOMB rating, describing it as "dreary, to put it mildly". Film critic Roger Ebert gave the film 1.5 out of 4 stars, panning the depiction of hell ("a post-nuclear Los Angeles created by animators with a hangover"), the premise of the film itself ("You would think that God would be the New England Patriots of this contest, but apparently there is a chance that Satan could win."), plot holes, inconsistencies, and general actions depicted throughout the film. He was not particularly critical of the film's acting, only mentioning it by stating, "Reeves has a deliberately morose energy level in the movie, as befits one who has seen hell, walks among half-demons, and is dying. He keeps on smoking." He added it to his list of "most hated" films.
I reckon the story is there via the character Constantine and the comic book series Hellblazer. A character that walks through all sorts of supernatural occurrences which he tries to handle with his arsenal of holy weapons and wits. However, the film in this case lacks balance and a script that keeps things together. The CGI is pretty average, we get a wooden Keanu (no surprise there..), wobbly dialogue, a cast with Shia LaBeouf, Tilda Swinton, Peter Stormare etc that seems to not be able to know what to do with their characters and a film that drags a bit during the running time. "Constantine" has a bit of entertainment value, but that is not enough.
Trivia: The character of John Constantine was originally created by Alan Moore, during his run on DC Comics' "Swamp Thing". However, following his negative experience with From Hell (2001) and The League of Extraordinary Gentlemen (2003), Moore decided to reject all money and credit from Hollywood on any adaptations of his work. Thus, he gave all the money he would've gotten to the artist who drew the character with him, and rejected his own "created by" credit from the film.
The original title, Hellblazer, was changed, because it was too similar to Hellboy (2004). The movies were scheduled to be released within a short space of time between them, and it was decided that having such similar titles would hurt the sales of tickets. Therefore Hellblazer was changed to Constantine.