After an 'incident' one wet Friday night where he is found walking naked through the streets of Cambridge, Professor Andrew Martin is not feeling quite himself. Food sickens him. Clothes confound him. Even his loving wife and teenage son are repulsive to him. He feels lost amongst an alien species and hates everyone on the planet. Everyone, that is, except Newton, and he's a dog.

Who is he really? And what could make someone change their mind about the human race . . . ?