A paleontologist lately returned from an expedition to Wyoming, where he unearthed the bones of the first brontosaurus (and supplied guns to the Indians on behalf of the Foreign Office, which had succeeded in its policy of balkanizing the North American continent) Mallory comes into possession of the MacGuffin during a Derby Day encounter with Byron's daughter (and Babbage's protégée) Ada. Thereafter he is hounded by a whole rogue's gallery of villains bent on reclaiming the MacGuffin.