The doorbell rings, just days after my beloved husband's sudden death. I don't recognise the woman on our doorstep, with a bouncing baby boy in her arms.

As I show her inside, I notice her eyes grow wide as she glances at the silver-framed family photos and my little daughter hiding behind my skirts.

She looks at me, her blue eyes serious. 'I'm sorry' she says. 'I know this will be hard to hear. But I am your husband's girlfriend. And this is his son.'

An utterly gripping psychological thriller from the number one bestselling author of The Marriage. If you like Gone Girl, The Girl on the Train and Lisa Jewell then you will be hooked by The Girlfriend.