Ashes to Ashes (2008) - 2x04 - Episode 4

There's a visitor from Gene Hunt's old stomping ground of Manchester. Jackie Queen is a journalist who's had run-ins with Gene in the past and this time she has a surprise in store. Not one to miss out on a story, she's also investigating the disappearance of northern teenagers that have arrived in London. She wants help to find one in particular: Rachel, her niece, who has run away and Jackie fears has been lured into the seedy underbelly of the capital.
Alex is suspicious of Jackie, and with the threat of a transfer haunting Gene, she's desperate they get to the bottom of the corruption she believes is in the force. But as the investigation progresses, evidence leads them to a man named Jarvis. On the surface he's a legitimate business man, but they are convinced that he's responsible for the murders of young girls.
With an expensive solicitor and smug demeanour, Jarvis appears untouchable, and what's worse, seems to have protection from within the Met itself. As the pressure mounts to find Rachel, the team are forced to acknowledge that the force is being poisoned from the inside. Gene's loyalty is tested as he and Alex are forced to stop to it, however messy the consequences.