Ruth witnesses a man killing himself and is troubled - was he trying to give her a coded message by handing her a marked ten pound note? At a local grocery shop, she's given a disc in exchange for the note. When she leaves, she's arrested.
Meanwhile, Harry, suspecting a cover-up, questions the report on a fire at Cotterdam Prison in which seven terror suspects died.
It transpires that the man who committed suicide was a special branch officer who had evidence that Ruth was colluding with the Cotterdam terrorists. The disc turns out to be blank and CCTV footage of the suicide has been tampered with to show Ruth committing murder.
The team realise Ruth has been set up. Adam discovers that the terrorists' deaths were faked to enable them to be tortured, and that Oliver Mace is responsible. Mace owns up to Harry but blackmails him: if he won't support the ongoing cover-up of the torture of suspected terrorists, he'll take Ruth down.
As 'evidence' continues to stack up against her, Ruth decides to admit colluding with the Cotterdam terrorists so Harry doesn't have to support the cover-up. As a result, Ruth has to fake her death and disappear for good.