Daniel Craig's character, Mr. XXXX (his name is not mentioned, and will be henceforth referred to as Craig) opens the movie, with a narration into the illicit drug industry and the billions of dollars it is worth. He doesn't reveal his name, because "If I told you that, then you'd be as wise as me." He considers himself a 'businessman whose commodity happens to be cocaine- not a gangster.' We discover that Craig is a middle-man drug dealer, who is planning on an early retirement having earned a nice little fortune for himself.
We're then introduced to the various people in Craig's world. The camera cuts to a group of 'loud wannabe gangsters' in Amsterdam, one slightly crazy Duke who works in the Craig organization, his girlfriend Slasher, and second in command, Gazza. We also meet Morty (George Harris) and Terry (Tamer Hassan), two guys who watch Craig's back. Morty is a thug like character, with ties to the criminal world. We then see Craig paying his head supplier, Jimmy Price, and the payment is picked up by Price's right hand man, Gene (Colm Meaney). Gene mentions that Price wants to meet up with Craig for lunch.
Over lunch, Price gives Craig an assignment- to find the daughter of one of his dear old pals, Eddie Temple (Michael Gambon, aka Dumbledore). She's hooked on cocaine and has gone missing somewhere. Craig is reluctant to take the job, but Price basically forces him to take the job. Meanwhile, we find that the crazy Duke and Slasher have hijacked a shipment of a million Ecstasy pills from a bunch of Serbians, who are understandably pissed that they've been robbed. Unfortunately for Craig, during the hijacking, Duke carelessly throws Craig's name around, which is the start of many troubles for Craig. The Serbians hire a hitman named 'Dragan', who has a penchant for putting his victims' heads into coolers, to track down the responsible. Furthermore, Price wants Craig to negotiate a purchase with Duke for the stolen pills.
Craig meets two pals in a club, Cody and Tiptoes, to ask them to find Temple's daughter, while he tries to secure a buyer for the pills. He bumps into Sidney, Duke's nephew, who has an incredibly hot girlfriend, Tammy (Sienna Miller). Craig is instantly smitten, as he locks eyes with Tammy. Meanwhile, Dragan has already struck, killing a lower rung member of Craig's group, Paul the Boatman. Paul, it seems, had Craig's cellphone number, as Dragan wakes up Craig early one morning with an ominous phone call. Craig decides to borrow a Luger pistol from Gene for protection.
With a bit of downtime, Craig phones Tammy, and she comes over to his room for a tryst. Before they can have sex, Craig is kidnapped by men posing as room service. He's taken to Eddie Temple, who reveals that Jimmy lost millions of dollars in a bad investment, thanks in part to Eddie. Jimmy has kidnapped Charlotte, to force Eddie to help him get his money back. Jimmy purposely assigned Craig to the job, knowing that Eddie would find Craig trying to track his daughter down, and kill him for it. Thus eliminating Craig, a smart young potential rival, and getting his money back at the same time. All of this is revealed in a tape recording of Jimmy, who also turns out to be a police informant. Temple also blackmails Craig into selling him the pills.
Incensed, Craig uses the Luger pistol that he borrowed from Gene to kill Jimmy. Woops- Gene realizes this much when he reads the ballistics report from the police, and proceeds to beat the heck out of Craig. Craig manages to convince Gene otherwise by letting him listen to the incriminating tape recording. With great timing, Dragan calls again, and sets up a meeting with Craig to hand over the Duke, and the pills. Unfortunately, the Duke and the pills are nowhere to be found (and it turns out that Gene had Duke and Slasher both executed), and the ex-Duke gang has gone under the radar.
Craig goes off to meet Dragan, but decides to bring a little insurance along- his own sniper to eliminate Dragan. In a surprising sequence, Craig's hired sniper is killed by Dragan, and Dragan threatens Craig once more, by giving him just one more day to turn over the pills and Duke. Fortunately, Craig and his buddies are able to track down the ex-Duke gang, now led by Gazza, thanks to the carelessness of Sidney. Gazza and Craig are negotiating the sale of the pills, when the police arrive and confiscate the pills, while Craig, Gazza, and the gang escape by boat. At the end of the day, Craig meets with Dragan, and presents him with the head of the Duke, which he obtained from Gene. He also tells Dragan that the pills have unfortunately been seized by the police- Dragan reveals that he observed all of this. Happy with the Duke's head and the pills in no one's hands, he reports back to his Serbian bosses, who are also satisfied.
It turns out that the 'cops' were actually men hired by Cody and Tiptoes, and Craig is actually in possession of all the pills. Craig takes the pills to Eddie, who shortchanges Craig by paying him only half of the agreed upon price, thanks to all the 'troubles' that Jimmy and Craig gave him. However, Craig had second guessed Eddie's intentions, and passed along the information to rival dealers, who ambush Eddie's pill truck and seize the pills.
We cut to the end scene, where Craig is at a country club, preparing to go into his early retirement. All of his buddies are toasting him, and eating layer cake. He leaves, and walks out with his girlfriend, Tammy. As he turns to tell the camera that he's quitting because he doesn't want to end up dead, Tammy gives a brief scream, and Craig is suddenly shot in the chest. As he lies dying on the pavement, a jealous Sidney runs over, says 'I'm sorry', and runs off.