Much like Greene’s earlier creation, Tom Corbett, Space Cadet, the series chronicles the adventures of a group of intrepid adolescent boys, led by boy hero Digby “Dig” Allen. The setting centers on the asteroid Eros, which is discovered to be an immense alien spacecraft. In every installment, the boys embark upon interplanetary voyages around the Solar System that are set against nefarious schemes from a variety of adversaries.