Edward Forester, a genetic researcher working for the Ministry of Defence, is an expert on primate hybrids. But even he is surprised when he succeeds in breeding a human/gorilla hybrid. Hybrids rarely survive more than a few days, but Gor - as he is called - grows from strength to strength, losing his hair and looking more like a human baby every day. When Colonel Lancing of the MOD orders Forester to destroy the creature, the scientist is unable to obey. Taking Gor into his own home and raising him as a human alongside his own daughter is Forester's only opinion. But it is a course that, one day, will have dramatic consequences ...