To The Manor Borne (by Robots)

 A terrible behemoth from out of space/time invades the 25th century, ravaging the world, killing millions. Its only weakness is stories, rendering it dormant. It's been contained within the Manor, a vast country estate controlled by the Master, the ruler of the future Earth, and the only person the Beast will let read stories to it and live. The Master transports his ancestor, office-worker Bob, from the present to the 25th century. Bob must substitute for the Master, while the Master travels to our time to unravel the mystery of the Beast's origins.  The story read to the Beast in this episode is No Fatties, Please, about an outlaw biker’s search for love, and the hunt for Osama Bin Laden.