A Dalek betrayed its kind during the events of the Master's Dalek Plan. It believed that the creation of the Daleks was meant to protect the Kaled race, but that the Daleks had fallen too far from that purpose. It contacted the Thirteenth Doctor to reveal their plans, unaware that it was being manipulated by the other Daleks to bring the Doctor to them. Upon arriving, the Dalek allowed the Doctor to copy information from its casing before three other Daleks, including the commander, arrived and killed the traitor.
After the Dalek mutant inside had died, the Daleks imprisoned the Doctor in its casing and took her to 1916 to meet with the Spy Master. (TV: The Power of the Doctor)
Behind the scenes[]
- In the original script, the Dalek — named "Spy Dalek" — identified itself as an elite biological combat engineer whose mission was to devise strategies to ameliorate any Dalek defeat in battle, its work resulting in a genetic code which was to activate and self-execute Dalek creatures in the event of a threat to Dalek supremacy in battle, causing their casings to flood with toxic radiation and detonate, fatally damaging all enemies within a broad radius.
- The Traitor Dalek is the fifth onscreen Dalek to realise the evil of its own kind and turn on them, with the others being Metaltron, Dalek Sec, Dalek Caan, and Dalek Rusty (not counting Clara Oswald, as she was a human who was forcibly converted into a Dalek).
