Here comes a candle to light you to bed - Maggie Prince

After her parents' divorce, Emily and her mother and brother have to move to a tiny old house in an undesirable part of London. It's a difficult adjustment for all of them, and made harder by the uncomfortable atmosphere of the house. Then Emily finds out that it was lived in by plague victims in the seventeenth century. Their spirits will not rest
especially that of Seth, a boy who finds her as fascinating as she does him. How can they reach out to each other across three hundred years?
A strong contemporary story is interwoven with a vivid and horrific account of plague-ridden London to make a gripping story of the supernatural.