Goth Girl And The Ghost Of A Mouse By Chris Riddell

(Used, hardcover)
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Meet Ada Goth. She lives in Ghastly-Gorm Hall with her father, Lord Goth, lots of servants and at least half a dozen ghosts, but she hasn't got any friends to explore her enormous, creepy house with.
Then, one night, everything changes when Ada meets a ghostly mouse called Ishmael. Together they set out to solve the mystery of the strange happenings at Ghastly-Gorm Hall, and get a lot more than they bargained for...