Gwen Cooper turns up on Martha Jones's doorstep with a dead body in tow. She needs to ask one final favour of her. And to find out why they stopped being friends.

A lot's happened to Torchwood since Martha left. A lot's happened to Martha since she left Torchwood. And there's something very odd about the dead body Gwen's brought with her.

Tonight Gwen's going to be getting more answers than she bargained for.