Episode: Certain First Principles. The Invisible Man reveals his true identity to Kemp – Griffin, Kemp's old university colleague. Recovering from the gunshot wound, he tells Kemp the story of how after leaving university, he discovered the formula for making himself invisible, but wound up alone and stray on the streets of London, struggling to survive in the open while unseen by those around him. He has been trying ever since to reverse the experiment, but he has other plans which involve Kemp himself...