After murdering two orderlies, Robert Griffin escapes from the secluded Cape Town mental institution where he has been committed, and now he is looking for revenge on the respectable Herrick family. A family consisting of Sir Jasper and lady Irene, and their daughter Julie, who are engaged in entertaining, and inspecting, Julie's new boyfriend, newspaper journalist Mark Foster, in the family residence. Later that night Julie and Mark leave the residence together, and Sir Jasper and lady Irene are left alone. That's when Robert decides to pay the couple a visit. Quite unexpectedly he enters the residence and accuses the couple of leaving him to die out in the African wild, injured when they were on a safari together. The Herrick couple defends themselves, claiming they were told that he was dead and not injured, but Robert doesn't buy their explanation. He demands they give him his share of the diamond fields they all discovered together on the safari. Jasper tries to tell Robert that the diamond fields were all lost in a series of bad investments. Robert refuses to give in, threatening to sue the Herricks, and to calm him down and get him off their backs, they offer him a share in an estate, the Shortlands. His counter-proposal is that they should arrange for him to be married to their daughter Julie. After saying this, he is drugged by Lady Irene and passes out in their home. The Herricks realize that their old friend and companion has gone completely mad, and while they are frightened of what he could do to them if they don't comply to his wish, they see no problem with stealing the agreement made or pushing him further along the path of insanity with their betrayal. They search Robert's clothes and find the written partnership agreement they all entered into some time ago. Taking the paper, they next callously throw Robert out of their house. Robert nearly drowns where he lies, unconscious, but is saved by a local Cockney cobbler by the name of Herbert Higgins.