Ben Aaronovitch & Andrew Cartmel 
Rivers of London: Black Mould #1 
Black Mould #1

It creeps! It crawls! It ooooozes! Something dark and slimy is dripping through the walls of suburban London. Not usually a police matter but there“s something very weird about this mould. Police Constable Peter Grant and his unwilling partner, Sahra Guleed, soon find themselves knee deep in killer muck! Meanwhile, their boss, Thomas Nightingale, is preparing to do battle against a haunted ice cream van. Good times.