In P. D. James's The Children of Men, the activist group seeking to save humanity is called the Five Fishes. The group is made up of dissidents who oppose England's increasingly authoritarian government and campaign for political reforms in a world facing total human infertility.
The Five Fishes approach Theo Faron, a former activist who has become a cynical government bureaucrat. Led by Rolf, with Julian among its members, the group asks Theo to use his connection to his cousin Xan, the Warden of England, to press for a return to democratic government and other reforms.
The group's name has a religious resonance, recalling the biblical story of the loaves and fishes. That symbolism fits the novel's concern with faith, fertility, and the survival of human society, but the Five Fishes are not simply a benevolent underground movement. Their tactics become increasingly militant, and internal conflict eventually exposes competing ambitions for political power.
The 1992 novel differs substantially from Alfonso Cuarón's 2006 film adaptation. The film retains a group called the Fishes, but its plot, characters, politics, and treatment of humanity's possible future are notably different.