From the scenario:
Annabelle Gillick, a one-time Delta Green ‘friendly’, is becoming a danger to the people around her. Gillick, a psychic, was assisting a Delta Green agent just over two years ago when her sensitive mind was exposed to alien emanations projected by an otherworldly entity. This drove her mad and until recently she has been in a catatonic state, waging and slowly losing an internal war with the nightmare impulses that have infected her. Her control is slipping, and her damaged mind is projecting echoes of the creature's terrible consciousness to those around her – to caustic effect. Enter the player-characters; A-Cell just learned about Gillick, and are concerned she is a security threat.