Gatehouse starts looking for Andy Dixon, who witnessed the shooting of drug-dealer Harvey Wratten - who was granted a Royal Pardon, in exchange for helping the police with drugs investigations.
Gatehouse visits Andy's mother, and tells her that, when he next contacts her, Andy is to phone him - and no one else. He also does the same thing with Andy's girlfriend. Sometime later - whilst Andy's girlfriend phones Jay Wratten (Harvey's nephew) instead - Andy's mother phones Gatehouse.
After an ensuing chase which Jay and DI Jonah Gabriel chase Andy through a park, they then lose him at the local train station - where Andy meets Gatehouse in the subway, and he is then taken to Liverpool. Gatehouse disposes of Andy's phone in another man's coat, to send the police on a wild goose-chase.
Later, after an exchange between Gatehouse and Andy, in which Gatehouse lectures him for things not going according to plan, he tells Andy to visit Jay and tell him everything he knows about Harvey's shooting. After Andy does so, Gatehouse kills both him and his mother in cold-blood - only to then make it look like Andy killed his mother, before then killing himself.
Following that, Gatehouse visits the son of former business partner, Peter Glickman - who tells him that he really does not know where his father is. Even though he knows this is true, Gatehouse takes drastic measure to find out exactly where Glickman is.
He tricks Glickman's son's wife into letting him into the house, and then asks her if he can use the downstairs toilet. She lets him, and whilst he is in there, Gatehouse unbolts the window - making sure it looks like it is still locked - before then finishing in the downstairs toilet, thanking the woman and leaving the house, after bidding her good night.
However, when she is on the phone to her husband, she hears the baby crying on the monitor. Eventually, she goes upstairs - only to discover that her baby has gone. But, she follows the sound of the baby's crying to the shed, where it is revealed that the baby girl is perfectly okay - but then, Gatehouse suddenly appears behind the wife, when she enters the shed to get the girl.
Gatehouse tells the woman that, if he had wanted to kill her baby, he would have done so by now. He tells her to tell her husband to phone her father-in-law, tell him about the baby and that Annalise (the baby) will be killed, unless Glickman contacts Gatehouse - and he also tells the woman not to call the police. Later, whilst Glickman's son is leaving him a message on his answer phone, telling him everything, Gatehouse is tracing the call, so as to find out where the signal from Glickman's phone is coming from.
The call is traced to Ireland, and Gatehouse later confronts Glickman in an antique shop that he is now running. Following the exchange between both men - in which both wield weapons - Glickman then blows up the shop and escapes. However, both men survive the blast and Gatehouse also flees the scene.
When journalist Ross McGovern becomes too meddlesome for his own good, Gatehouse phones up a colleague of his - and, pretending to be a delivery man, asks her for Ross's address. After she unknowingly gives him the information he wants, Gatehouse then sets up an ambush for McGovern - and kills him, as he is coming along on his motorcycle.
Later, Glickman and DI Gabriel set up a trap for Gatehouse - in which Gatehouse comes to visit Gabriel, and is invited into his house. There, Gatehouse gives Gabriel a diary, which tells him everything that he has been searching for answers to. However, the following exchange soon leads to Glickman killing Gabriel's illegitimate child that he conceived with his mistress, and hospitalising Gatehouse - Gatehouse having been left lying on the floor, in a pool of blood.
As an act of mercy, Glickman is later killed by his wife, who he has only recently been reunited with. His wife later goes to visit Gatehouse in the hospital, intent on killing him. As part of her plan, she measures the timing of his heart beats on the monitor - but, she waits too long, and Gatehouse eventually wakes up and kills her, anyway. He carefully puts her in his place, and dismisses himself from the hospital.
Gatehouse later forces Police Commander Khokar to hang himself, outside Khokar's lovely country cottage. Gabriel confronts Gatehouse, and the resulting conversation reveals that Gatehouse has been behind everything that has been going on - including the police paying for drugs, and helping grant Harvey a Royal Pardon. Gatehouse also reveals he has two recruits on his side, in the form of Jay Wratten and Ratallack (an ambitious rent boy - whom Gatehouse does not mention by name, but mentions the fact that "he's good with numbers"), When Gabriel reveals that a sniper rifle has been trained on him (Gatehouse), courtesey of Lia Honey (a colleague of Gabriel's), the tide turns - and, in fact, the gun is actually trained on Gabriel, and not Gatehouse. Gabriel is then killed, by Honey - who Gatehouse manipulated into serving his corrupt cause.
In the end, we see Gatehouse with Jay Wratten and Ratallack, starting to build a new criminal empire - following the deaths of Gabriel and Joseph Bede (a drug-smuggler who would've simply retired, where it not for Jay).