Midnight Riot
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Funny, gripping and nail-bitingly tense in equal measure. The story follows a new policeman on the beat in London as he suddenly discovers he can see ghosts. Also, that the Met has a unit just for such instances as these.
Part detective story, part police procedural, part supernatural thriller. The book comes across well and mixes all genres into an amazing whole, with good characters and locations.
Like Neverwhere, will make you see parts of London in a different light.