Brave and utterly gripping, this is an edge-of-your-seat tale of survival that will delight fans of The Boy in the Tower, Orphans of the Tide and Crater Lake. Filled with all of the chills and thrills that you’d expect of Polly Ho-Yen’s dystopian middle-grade stories, the story is also served with a generous helping of emotional poignancy that explores themes of family bonds, mental health, learning to trust and never giving up on those you love.

Sylvia has always taught her son Billy the basic rules of survival; always be prepared, pay attention, trust no-one, master your fears and never stop trying. Sylvia loves taking Billy on outdoor adventures and ensuring that he is as ready as possible for surviving whatever may come their way. But Billy knows that his mum’s behaviour is different from other parents. Her actions become increasingly erratic, and she soon removes Billy from school altogether to prioritise survival lessons. After a crisis weekend when one of their survival lessons goes awry, Sylvia is admitted to hospital for mental health help, and Billy is sent away to live with his Dad in Bristol. Billy knows more than anything how much Sylvia loves him, but now he feels alone, confused, and cross with the grown-ups who do not seem to think that Sylvia is able to look after him well. Among the strangeness of living in a new place, Billy notices other unexpected things starting to happen. Before long, a mysterious virus seems to take hold in the local area, turning people into zombie-like creatures called ‘Greys’. Suddenly, the world appears to change in the blink of an eye, and Billy and his new family embark on a race against time when his survival instincts will be more important than ever.

Like the very best dystopias, Polly Ho-Yen’s sci-fi worlds always feel just the smallest step away from our own and after the past year, reading a virus-themed story feels both daunting and relatable. The fast-paced virus escape scenes are quite frightening in places, but the zombie-esque appearances of the victims helps to maintain a fictional edge that stops the tale becoming too close to home. There’s a well-crafted mirroring between the physical virus taking hold of the community and the mental health crisis that has been gaining a grip on Sylvia’s mind over a number of years. Billy’s character development in the story is beautiful, and by the end of the narrative, he has formed a good set of real-world survival skills of his own that will help him to navigate the ups and downs of growing up and making trusting relationships with others.

This is an exciting thriller that packs an emotional punch and leaves you rooting for the main character. It’s not for the faint-hearted, but is sure to thrill mature readers in KS2 who love a page-turning plot with a rollercoaster of emotions and a few truly nail-biting scenes to get stuck into.