When Ted Hughes's "Birthday Letters" was published in 1998, it was greeted with astonishment and acclaim, and immediately became a bestseller. Few suspected that Hughes had been at work for a quarter of a century on this cycle of poems addressed to his first wife, Sylvia Plath. Erica Wagner explores the destructive relationship between the two poets through their lives and their writings. She provides a commentary to the poems in "Birthday Letters", showing the events that shaped them and showing how they draw upon Plath's own work.