Captain Turner manages to rescue Jamie and the others, while the Doctor begins working on a way to protect everyone from the Cybermen's hypno-sound signal.

With the entire world unconscious apart from the Doctor and his friends, the Cybermen are poised to invade and only Zoe, the Brigadier and a missile crew can stop them.

The Cybermen have launched their deadly megatron bomb which will destroy all life on Earth unless the Doctor can deactivate the homing signal.