These are mysteries with historical and cultural content. Mortensen is a fun and good-natured hero who trots the globe and travels throughout history. Educational back matter offers the readers more information on the topics covered.

Mortensen is tasked with delivering the ransom for a kidnapped scientist, but nothing is as simple as it might seem. The scientist's kidnappers are time travelers, and they have abandoned him in the year 1901. Before Mortensen can deliver the ransom, he is drugged and packed in a shipping crate headed for Africa. With the help of an archeologist and a pilot he meets along the way, Mortensen is able to find the scientist and unravel the secret behind the rare metal he was studying.