Part one:

Over the last few decades, Dublin has undergone a massive renewal program that has seen it turned into a city that attracts tourists from around the world. Although this transformation has been far reaching, there are still parts of the city where no tourist would want to visit. It is here that mild-mannered civil servant Sean and his lifelong friend, Mickey Dooley, meet up to reminisce and talk about their past.

When the reckless and undependable Mickey agrees to an ill thought-out loan agreement with a stranger, he enters into a world of fear and evil, the likes of which he could never have anticipated.

As Mickey's deal crumbles, Sean finds himself being dragged into a sinister world he does not fully understand. In a situation that will test their friendship to the limits, Sean soon learns that he is dealing with no ordinary loan shark.

Part two:

Mickey Dooley has disappeared. After entering into a loan agreement with the terrifying loan shark, Martin, in a deal that seemed doomed right from the start, the incorrigible Irish rogue Mickey is forced to go into hiding. He seeks shelter with his longtime friend, Sean, who really has very little understanding of the ins and outs of how the underworld works.

Once Martin learns of Mickey's whereabouts, both he and Sean find themselves on a roller coaster ride of fear from which there seems to be no escape. The diminutive, unassuming-looking loan shark is able to anticipate their every move and responds with disproportionate brutality that has an almost demonic aspect to it. Sean finds the entire situation terrifying, but there is no way out. As he is sucked further into the whole monstrous scenario, he is forced to confront flaws in his own character.

Part three:

Sean's life has been turned into a living nightmare ever since he sheltered his friend, Mickey, from debt collector Martin. The innocuous-looking loan shark seems to have an almost diabolical ability to foresee any attempts to evade him and is ruthless in punishing anyone who tries to.

When Mickey is found savaged, bleeding, and missing one of his fingers in a remote part of the Irish countryside, Sean knows that it is not the result of a dog attack that the authorities believe it to be. He also knows that unless he takes over Mickey's debt, his friend will soon be dead.

The once beautiful ex-model, Kitty Parks, warns him to steer clear of Martin, but she pays for that warning with her life. An attempt by Sean to recruit the help of the police is met with scorn, and so he finds himself drawn even deeper into the sinister affair.