Delta Green is the clandestine American programme — a black-budget intelligence operation — dedicated to identifying and containing Mythos threats. Its standing orders, as recited by the GM, are: stop the incursion, obscure the incursion, obscure Delta Green's involvement, secure advanced technology, save lives — in that priority order. The organisation operates through isolated cells, uses coded communications for field emergencies, and maintains relationships with programme-friendly personnel for handling contaminated witnesses.
H-Cell are Delta Green operatives whose work in the H-Cell Chronicle sits at the intersection of a modern Dorset investigation and a WWII North Africa operation. Delta Green's relationship with its British counterpart PISCES is described as historically not easy but maintained as professionally friendly. The cell operates largely without active Delta Green support during the campaign's events, relying instead on PISCES liaisons, military contacts, and their own judgement.