In the episode, Tia Karim, a rogue member of UNIT allies with members of the Shansheeth alien race to lure Sarah Jane and Jo into a trap so they can access the Doctor's time machine, the TARDIS, and change history and Karim can leave Earth, with the cover story of the Doctor's funeral.
Members of the Shansheeth, a race of alien vultures, lure the Eleventh Doctor to the Wasteland of the Crimson Heart, and strand him there.
The Doctor travels 10,000 light-years to repeatedly swap places with Clyde, who still has residual artron energy from when he touched the TARDIS.
Sarah Jane and Jo safely shield themselves with the lead-lined coffin that they were fooled into believing was where the Doctor's body was.
In some of Sam Watts' music, vocals were provided by Jodie Kearns, wife of Doctor Who and Torchwood writer James Moran.
[4] Released as part of The Complete Fourth Series, (Season in America) on DVD, Blu-ray is a UK exclusive.