Captain Jack Harness was out on a mission for Torchwood, hunting the streets of Cardiff for Weevils when, suddenly, he heard a sound that shocked him back to his core. He hadn't seen the Doctor since the Daleks had stolen the Earth, so Jack started sprinting towards the source of that mysterious yet oh-so-familiar noise.
Just as Jack turned a corner and saw the TARDIS materialising, he saw it fade away just a second after. Jack knew that the Doctor must have seen him and tried to run away, but Jack knew that he would catch up with that quirky timelord one day.