Plot Summary:A British Airways Concord disappears on final approach. The Doctor, still reeling from the loss of Adric, becomes involved when his TARDIS miss-fires from its intended destination of London 1851 and appears at Heathrow airport. The Doctor follows the lost plane into the deep past only to discover he is part of an illusion. This forces him to ask the question: if there is an illusion, who is the conjurer?
