Doctor Who fan fiction.
A story that combines the Seventh Doctor and his companion Ace with the DC Comics villain (and nemesis to DC hero Batman), the Joker.
Deciding to fly in a commerical airline rather than travel in the TARDIS, the Doctor and Ace find the place hijacked by the homicidally insane Joker, who begins killing passengers, beginning (apparently) with the Doctor.
Part 1 appeared in issue 4 of Burnt Toast; part 2 appeared issue 5 of Burnt Toast.