In the same episode, Section D learns that Collingwood is plotting a conspiracy to overrule the Prime Minister, and launch measures to combat terrorism, at the cost of several civil liberties.

[3] In the second episode, Ros learns that her father, Sir Jocelyn Myers, is funding the conspiracy, and she persuades him out of it, as the rest of the team stop Collingwood.

[4] In the fourth episode, she is angered to learn that despite Harry Pearce's (Peter Firth) promise of going easy on her father, he is instead sentenced to 20 years imprisonment.

Though Adam and Malcolm Wynn-Jones (Hugh Simon) stop the attack, one of Yalta's high-ranking members, Juliet Shaw (Anna Chancellor) supposedly kills Ros for her betrayal by injecting her with poison.

[10] In the next episode, Harry promotes Ros to succeed Adam as Chief of Section D.[11] In later episodes of the series, Ros works to uncover an FSB mole within the section, who is attempting to sabotage "Sugar Horse", a top secret MI5 operation involving the recruitment of Russians into top government positions, and therefore, become aware of Russia's intentions towards the United Kingdom.

[13] However, in the finale, she and Lucas North (Richard Armitage) are forced to use her help when they discover "Tiresius", Russia's equivalent of Sugar Horse, has planted a nuclear bomb in London.

Later in the episode, Colville finds a way to hack into MI5's records through Ros' account to kill every officer responsible for the death of Mina, his love in Bosnia several years before.

To put a stop to it, Ros and Lucas attempt to rescue a paralysed Pakistani President Mudasser and Home Secretary Andrew Lawrence (Tobias Menzies) from a hotel rigged to explode.