PISCES — the Paranormal Intelligence Section for Counterintelligence Espionage and Sabotage — is the British government's equivalent of Delta Green: a clandestine programme tasked with investigating and managing Mythos incursions. Where Delta Green's philosophy tends towards destruction of threats, PISCES leans towards containment and study — a difference Hanover notes from occult circles. The organisation is described as having listening outposts that flagged the Dorset incident, prompting a containment team's dispatch, and it maintains a network of trusted contacts, facilities, and cover identities across Britain.
PISCES reaches out to Delta Green specifically because the filament heart situation requires specialist experience — Harry Lane acknowledges they needed help. The two organisations maintain a professionally cordial relationship despite historical tensions. In 1942, PISCES operates through Harry Lane's naval identity, deploying H-Cell on an off-books operation that becomes the WWII thread of the campaign.