Frank and Joe Hardy follow their father on a trip to Nairobi for an incredible vacation. Intrigue has a way of finding the Hardys, though, and in a short time they become involved in a dangerous case. Someone's hunting wild animals for prize skins and tusks, angering the area's animal rights activists. When Frank and Joe see some of the horrific work of the hunters while on safari, they become determined to help put an end to it.