1. Danny's death (Series 3 Episode 10)
As with many Spooks deaths, you wouldn't have expected it. Harry had to choose which of Danny and Fiona had to die and Danny makes the choice for him by calling the villain "a death worshipping fascist". He then gets shot in the head.
2. The deep-fat fryer (Series 1 Episode 2)
Lisa Faulkner, that lovely girl from Holby City was not only killed, but killed in a thoroughly gruesome way. It was done for impact and it worked. Everyone tuned in the following week. Cynical but, hey, it's TV
3. Adam's death (Series 7 Episode 1)
People knew Adam [Rupert Penry Jones] was leaving but, like Adam's exit, the details can still surprise. Frequently you read scenes and you think "They won't shoot that" and frequently they don't because it's too difficult or too implausible, but they really pulled it off with Adam's death in the car bomb.
4 Tom's decommissioning (Series 3 Episode 2)
You can usually tell when actors are destined for great things, and that was definitely the case with Matthew Macfadyen. When you see Matthew in full flow - as he was with Tom Quinn being forced to retire - you know that you're in the room with something special.
5. Colin wells's hanging (Series 5 Episode 1)
One of the Spooks' mantras has always been "Kill your heroes" - even if they're not right in the frontline. Geeky Colin was a fan favourite so his end was almost more shocking than one of the leads.
6. Zoe's happy ending (Series 3 Episode 6)

7. Connie kills Ben (Series 7, Ep 7)
This was a real coup de théâtre - and with the underwire from her bra, too. You never know you're going to make it through an episode until you've got the script - and even then it can change.
8. The bomb in Tom's house (Series 1, Ep 6)
For the climax to the first series we locked a mother and daughter in a house with a ticking bomb. That left me speechless.
9. Ruth says goodbye to Harry (Series 5 Episode 5)
This was a real wrench because it felt like Harry's chance at happiness slipped away.
10. Adam rescuing Ros (Series 6 Episode 8)
Two of Spooks' finest characters - and a couple of great actors Hermione Norris and Rupert Penry Jones - at the absolute top of their game in scenes that were both thrilling and poignant.