Doctor Who: Survival of the Fittest

On a distant world, the Doctor and Klein discover that the insect-like race that they have come to know as the Vrill have been all but wiped out by the mysterious and terrifying Winterlack. Discovering the true nature of the Winterlack, Klein is cast out of the Vrill nest into the jungle beyond. There, she is forced to confront the Winterlack threat alone. In the Vrill nest, the Doctor desperately searches for a way to save the Vrill from extinction. But the odds are against him, and time is running out...