De Maggio was an officer in Bywater's security detail in the Vault, in Henry van Statten's underground base in 2012. She was charged with getting Rose Tyler and Adam Mitchell to safety after van Statten's captive Dalek, nicknamed "Metaltron", broke free and began slaughtering her comrades.
The Dalek eventually caught up with the fleeing trio in a stairwell. At first, they thought the Dalek couldn't climb after them. De Maggio tried to negotiate with it, but to no avail and it elevated up the stairs towards them. De Maggio sent the youngsters on and staying behind, opened fire on the Dalek in an attempt to stop it, only to be exterminated. (TV: Dalek [+]Loading...["Dalek (TV story)"])
Another account identified the security officer as an Israeli named Maya Klein. (PROSE: Dalek [+]Loading...["Dalek (novelisation)"])