SPECIAL PREMIERE: Last fall, BBC America went back into its archives, and its bag of tricks, and emerged with something old and new: a restored version of the long-lost first adventure starring Patrick Troughton as the Second Doctor. That serialized story was called “The Power of the Daleks,” and was brought back to life using surviving audio recordings and newly generated animation, based on still photos taken during production. Now BBC America is pulling the restoration trick again – but this time on an episode of Doctor Who that was written and planned, but only partly produced, because of a 1979 engineering strike that temporarily shut down production at the BBC. It was an episode starring Tom Baker as the Fourth Doctor – a very popular incarnation of the titular hero – and was written by Douglas Adams, the same year he published his seminal Hitchhiker’s Guide to the Galaxy novel. It’s 1original live-action footage from the parts of the original story that were televised, starring Baker, with newly created animation segments, and even a new scene in which Baker reprises his role as the Doctor. Given that Doctor Who is all about a protagonist with the gift for inventive regeneration and reinvention, this “Lost Episode” seems only fitting.