Ben Aaronovitch & Andrew Cartmel 
Rivers of London [PDF ebook] 
Black Mould #4

Peter Grant and Sahra Guleed are trying to contain an outbreak of vindictive black mould that seems to be going after the rich and heartless. But after a successful mission, the mould has penetrated the headquarters of London’s crime-fighting magical practitioners — The Folly — and the shitake is about to get real…An all-new and original Rivers of London comic series, written by Ben Aaronovitch and Andrew Cartmel! Set between ‘Foxglove Summer’ and ‘The Hanging Tree’.