"Be very careful when you tune in to this edition of Panorama, or you could be fooled into thinking that Britain's in the midst of a national crisis after a string of terrorist attacks on London.
The programme makes extensive use of BBC News personnel, logos and "breaking news" banners to illustrate a terrifying doomsday scenario – a series of explosions on the London Underground and a chlorine gas attack.
With experts from the emergency, security and medical services, it asks just how prepared we are for such a deadly onslaught.
As you might expect, the answer seems to be "not very".
Just how will the emergency services be able to communicate with one another as they attempt to rescue potentially many hundreds of injured people from crowded Tube trains?
How can hospitals be expected to cope with enormous numbers of casualties suffering very specific injuries? And, above ground, how can police keep the capital's traffic from suffering a chaotic meltdown as thousands of people abandon their cars in fear and panic?
None of the experts seems terribly hopeful that devastation on such an unprecedented scale could be dealt with appropriately."