(The DOCTOR can be overheard addressing VAUGHN.) ...remaining on earth. MISSILE LAUNCHING RANGE. Raise all missiles! The Cyber-megatron bomb will be delivered. The radio transmitter's been destroyed, so the Cybermen can no longer deliver their bomb.
Plan: A: The Cybermen; Q: Who has launched their megatron bomb? A: their deadly megatron bomb; Q: What did the Cybermen launch? A: all life; Q: What will the Megatron bomb destroy on Earth? A: the homing signal; Q: What must the Doctor deactivate to stop the Megatron bomb? Summary: The Cybermen have launched their deadly megatron bomb which will destroy all life on Earth unless the Doctor can deactivate the homing signal.