Torchwood are called to investigate fatal injuries sustained by two burglars in the failed attempt to rob a flat owned by Beth Halloran and her husband Mike.

After numerous evaluations under the probe, they suddenly discover alien technology buried under Beth's right forearm, allowing it to transform into a bladed weapon that matches the injuries on the burglars.

William Hughes, who plays the Graingers' son, previously appeared as the eight-year-old version of the Master in the 2007 Doctor Who episode "The Sound of Drums".

Derek Lea, who plays the Sleeper Agent/Paramedic; also appears as a worker being examined by Martha Jones at the ATMOS factory in the 2008 Doctor Who episode "The Sontaran Stratagem" and as a taxi driver in "Partners in Crime".

[3] BARB later listed the episode as BBC2's top audience draw for week ending 27 January 2008, on a certified estimate of 3.78 million viewers including timeshift.