Ed and the River of the Damned — Andrew Fusek Peters

Ed and his friend Zack are on holiday in London, where Ed keeps noticing the particularly friendly and intelligent rats coming out of the cellars. Following a rat into an abandoned underground station, Ed finds himself on a weird journey into London's sewers and the forgotten River Fleet. Here he encounters mystical owls and Victorian sewer workers, but also the power to take on the drug-pushers who threaten to destroy the city's youth.