Skullduggery is a 1970 American science fiction film directed by Gordon Douglas, produced by Saul David, and stars Burt Reynolds, Susan Clark and Edward Fox.
The screenplay is based on the French novel Les Animaux dénaturés (1952)—variously titled in English as You Shall Know Them,Borderline, and The Murder of the Missing Link—by Jean Bruller ("Vercors").