All over the world, people are venting their fury at one another on social media. Dropping their friends, giving vent to their hatred, and everywhere behaving with incredible cruelty. Even Donna has found that her friend Hettie, with her seemingly perfect life and fancy house, has unfriended her. And now, all over the world, internet trolls are dying...

As more and more people give in to this wave of bitterness and aggression, it's clear this is no simple case of modern living. This is unkindness as a plague.

From the streets of London to the web cafes of South Korea and the deepest darkest forests of Rio, can the Doctor and Donna find the cause of this unhappiness before it's too late?

An original novel featuring the Tenth Doctor and Donna, as played by David Tennant and Catherine Tate.

Jenny T Colgan has written 16 bestselling novels as Jenny Colgan, which have sold over 2.5 million copies worldwide, been translated into 25 languages, and won both the Melissa Nathan Award and Romantic Novel of the Year 2013. Aged 11, she won a national fan competition to meet the Doctor and was mistaken for a boy by Peter Davison.