London sewers

The London sewers are a system of underground infrastructure meant to transport sewage from houses and commercial buildings in London through pipes to treatment or disposal.

At some point, there were Muggle complaints of 'wailing sounds' coming from plug holes and toilets; around the same time, wizard Philbert Chivers went missing and his wand was found at a sewer entrance. Suspecting there was some sort of magical creature in the sewers, Muggle Liaison Officer Myra Curio dispatched Department for the Regulation and Control of Magical Creatures investigators Mathilda Grimblehawk and her partner to look into the matter.