Ben Aaronovitch & Andrew Cartmel 
Rivers of London [PDF ebook] 
Black Mould #5

A sentient killer mould seems to be targeting the rich tenants of a shady property developer. Naturally, this draws the interest of the Folly’s Finest, PC Peter Grant and his boss, Thomas Nightingale. Their investigations lead to an old acquaintance of Nightingale’s with an interest in herbal remedies and, much to Peter’s surprise, old handguns…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’.