David Tennant's final series as the Doctor is full of fantastic stories, from the spooky Midnight to the blockbuster finale to the introduction of River Song in Silence of the Library. But another, somewhat underrated standout is The Fires of Pompeii.
Continuing the Tennant-era trend of having a historical episode come second in every series, this James Moran-penned disaster epic is the first proper adventure that the Doctor and Donna embark on together, after their reunion in Partners in Crime.
It's an important story in establishing that Donna isn't just a "comic-relief" companion, which many assumed would be the case when Catherine Tate was cast. Instead, Donna gives the episode a huge emotional wallop in her desire to save as many lives as possible, demonstrating exactly why the Doctor should never travel alone.
After writers like Russell T Davies and Richard Curtis took to Twitter to talk about their episodes The Stolen Earth and Vincent and the Doctor, James Moran recently did the same, joining Who fans around the world for a watch-along of The Fires of Pompeii.
In doing so, he revealed a bunch of cool behind-the-scenes details and unknown secrets about the episode, so we picked out the best ones you need to know!