Slipping out of school for a break, young Sarah-Jane Smith hangs out at the local allotments. Here she witnesses a flock of starlings transform into a huge skull-like formation and kill a passer-by. When the murmuration turns its attention to her, Sarah runs into the safety of a nearby police box - only to find herself in a gleaming-white control room, in the company of friendly alien called the Doctor. He explains that the starlings have been possessed by a Tononite, an alien force that has travelled to Earth through a rift in space.