Remembrance of the Daleks

With unfinished business to attend to, the Seventh doctor returns to where it all began: Coal Hill School in London in 1963. Last time he was here, the Doctor left something behind- a powerful Time Lord artifact that could unlock the secrets of time travel. Can the Doctor retrieve it before two rival factions of Daleks track it down? And even if he can, how will the Doctor prevent the whole of London becoming a war zone as the Daleks meet in explosive confrontation?