91Èȱ¬

Harry Pearce reawakens a 'sleeper': Fred Roberts, renowned chemical engineer, Nobel Prize winner and happy family man. Fred sold his soul to MI5 over twenty years ago in return for a helping hand on the career ladder.

Over the years this pact has become nothing more than a faded memory, but the time has come for Fred to repay his debt.

Harry and the team are running Operation Flytrap - they want to spread the lie that Fred has made Red Mercury, a lethal trigger for explosives, in order to attract terrorist groups. Harry approaches Fred, who is unwilling to sacrifice the happy and secure life he has made for himself. But Harry makes him an offer he can't refuse - don't co-operate and your life and reputation will be systematically ruined.

Tom, Zoe and Danny convince Fred that he has no choice. They have already dealt with his financial affairs: Fred is now in serious debt, desperate for money and would go to any lengths - including selling Red Mercury. Fred cracks and agrees. His wife, ignorant of the truth, flees the family home believing Fred is a gambling addict with debts and a vicious streak. Tom seems to be relishing forcing this man to become MI5 bait. He dismisses Harry's request to keep an eye on Fred's emotional wellbeing.

Meanwhile, Zoe has taken a liking to Will North, a photographer she catches skulking around. After he's been checked, she doesn't hold back from having a passionate fling. Soon enough Fred is approached by a terrorist suspect. He's offering $5 million for 5 grams of Red Mercury. Fred is warned - if it turns out he has dealings with MI5, his family is dead. The team trace the man - he's a chemistry postgraduate student, Lawrence Sayle, and his connection: he's part of the Syrian Secret Service and has Al-Qaeda sensibilities.

Fred begins to fall apart under the strain. Then cracks appear in Tom - he's beginning to care about what this is doing to Fred and his family. He pleads with Harry to put Fred's family into a safe house. Harry is unmoved. The family stays where they are, but Fred is to be told they are safe. Tom's increasingly troubled by Fred's exploitation. Harry refuses to cancel Operation Flytrap and Tom takes the decision into his own hands. The team catch up with Fred agrees to return with them. Harry is forced to de-commission Tom from the Service. His career with MI5 is over. Back at the lab, Lawrence Sayle comes to collect his Red Mercury and falls into a sting headed by Adam Carter. Operation Flytrap has been a success and Fred is free. So is Tom, who takes one last look at Thames House before he walks away for good.