|Series 04, Episode 10|
|Air Date||10 November 2005|
|Next||Gas and Oil (Part 1)|
Diana refers to the tenth and last episode of spook's fourth series which aired for the first time on 10 November 2005.
After former MI5 officer, Angela Wells visits Ruth, she comes to "The Grid" and holds everyone hostage, demanding the division find incontrovertible proof that Harry and MI5 conspired to kill Diana, Princess of Wales, or she'd detonate a bomb.
The team find the proof, but Harry admits this was just a worst case scenario in order to try and prevent her death. The team are able to trick Angela, and decide to let her go. However, she later plans to attack the Royal family, who are evacuated to a bunker, only to be rigged by a bomb. Adam defuses it, but upon returning to Thames House, Angela awaits and fires her sniper rifle, gravely wounding Adam, and is prepared to shoot Harry.