Hot on the heels of the news of Tom Riley's casting in series 8 of Doctor Who, we now know which story he will be guest starring in. That will be the third episode of Peter Capaldi's debut season, which will be written by Mark Gatiss. Also featuring will be Trevor Cooper, Ian Hallard, David Benson, Roger Ashton-Griffiths and Sabrina Barlett.This news comes from the latest edition of Doctor Who Magazine , which also reveals some details for episode 6. This will come from the pen of Gareth Roberts, and guest star Nigel Betts, Edward Harrison, Andy Gillies, Ellis George and Jimmy Vee. Both episodes will be directed by Paul Murphy.Source: DWM