The TARDIS lands in Cardiff to refuel, and the Doctor picks up a hitchhiker: Captain Jack Harkness, lately of Torchwood, who is not going to let the Doctor get away twice. The hand-in-a-jar that Jack's been carrying around in Torchwood turns out to be the Doctor's old hand, which Jack's been using as a "Doctor detector". With a dramatic cry of "DOOOOCTOOOOOOOOOOOOOOR!", Jack leaps onto the TARDIS as it's disappering. It turns out that the TARDIS does not like Jack ever since he Came Back Wrong, and rejects him, hurling through time and space in an attempt to shake him off. Jack ends up dead when the TARDIS lands on a lonely dark planet trillions of years in the future. But everyone except Martha knows that death is pretty temporary for Captain Jack.