He was the shameful cause of his sister Elena's death, and he stole state papers from England, yet Adrian Hart is feted by the best of society in Rome and boldly dubs himself "Iago".

Determined to avenge Elena, his unrequited love, Lieutenant Andrew Sullivan asks the advice of poet and Shakespearean John Keats and his artist friend, Severn. Soon, Percy Bysshe and Mary Shelley join them, then Lord Byron and his servant, Fletcher.

But how can the seven of them work against this man when they can't even agree what he is? The atheist, Shelley, insists that Hart is an ordinary man, while Byron becomes convinced he's the devil incarnate, and Keats flirts with the idea that he's Dionysius....

As death and despair follow in Hart's wake, Sullivan knows he must do something to stop Hart before even Sullivan himself succumbs - but what?