A grim discovery in a Swedish lake reveals shocking ancient practices. Meanwhile, in the Canadian Arctic, the fossil of a previously unknown mammal is found.

In a Danish bog, hundreds of mutilated ancient bones are found, while a mysterious deserted island belonging to Russia is explored.

Human remains are discovered high in the Ecuadorian Andes, while a strange earthquake-like event is investigated in Canada.

In Russia, 34,000-year-old graves are discovered. Meanwhile, a team attempts to locate a British World War II aeroplane that went missing in Iceland.