WPC Gwen Cooper is at the scene of a brutal murder, when the "special ops," known only as Torchwood, arrive. After witnessing the group bring the dead man back to life, Gwen goes in pursuit of this mysterious organisation, only to see weirder things than she could ever imagine existed. Soon after, she begins to regret giving in to her curiosity, when she meets Captain Jack Harkness.

Whilst chasing a man, Gwen retrieves an unusual machine that allows the user to see back into the past. It is considered dangerous, and no members of Torchwood are permitted to use it. But Owen has other plans, and witnesses a violent murder that took place over forty years ago. Using the information he gathered, Owen starts to track down the still-living murderer.