Sign of the Raven — Julie Hearn

Something odd is going on in the basement of an old house in London. An inexplicable gap has formed, a gap in time that links the present to the past. And twelve-year-old Tom, who discovers the gap while on a visit to his grandmother, is torn between both worlds.

Lured by a mysterious voice, Tom leaps into the early eighteenth century, to a time when circus "freaks" like the Bendy Man and the Gorilla Woman appeared at Bartholomew Fair. The voice he hears belongs to Astra, a tiny changeling child, whose limbs are no bigger than a man's thumb. She has called him into the past, because she is convinced that Tom is the only one who can help her and her friends from danger. Doctors are paying a high price for unusual bodies to dissect, and Astra and her friends are prime subjects.

But Tom is dealing with difficulties of his own. His mum has cancer and is constantly fighting with his gran. And then he discovers a dark secret in his family's past...a secret that pulls the strands of time together and might just close the gap forever.