Helena Coggan wrote the first draft of her debut novel, The Catalyst, when she was thirteen. It was published two years later and was named as one of 2015's Debuts of the Year by the Guardian and Amazon, and featured by The Sunday Times, the Observer, the Daily Mail, the Sun, the Daily Metro, the Sunday Express, Radio 4, NBC, and BBC Breakfast. Up until she started writing it, she spent most of her time waiting for her Hogwarts letter to arrive, or for the Tardis to appear in her garden; she would like to pretend she has stopped doing this now, but doubts she ever will. She lives in London with her parents and sister, and spends most of her time suppressing the thought that she should probably be doing her homework. The Reaction, the sequel to The Catalyst, is her second novel.