After doing more research, she turned up at 10 Downing Street claiming to be seeking an interview with Lucy Saxon. She told Lucy the truth about Saxon, explaining that he had only been in existence since Harriet Jones' downfall. However, Saxon had already told Lucy about his true identity and intentions, and Saxon himself came in and ordered four Toclafane to kill Rook.
However, she had a contingency plan and prepared an email message to be sent to Torchwood if she hadn't returned to her desk by 10pm that day. It was retrieved by Jack Harkness, the Tenth Doctor and Martha Jones on Martha's laptop. Vivien had attached the Saxon files, including the Archangel document, which allowed the three to find out how Saxon had mind-controlled most of the world and use it against Saxon. (TV: The Sound of Drums)