BRENT: But... Control centre of the present system is the moon, serving receptions at all major cities on the Earth. Er, this is Zoe, Jamie and I'm the Doctor. PHIPPS: I'll switch on the power. T-Mat the ultimate in travel. There is just one man, one man alone who can help us now!
Plan: A: 21st century; Q: In what century is Earth entirely dependent on the T-Mat transport system? A: the control centre; Q: What has stopped working on the moon? A: the crisis; Q: What does the Doctor, Jamie and Zoe meet the one man who can solve? Summary: 21st century Earth is entirely dependent on the T-Mat transport system but the control centre on the moon has stopped functioning. Meanwhile, the Doctor, Jamie and Zoe meet the one man who can solve the crisis.