 As the Lensmen trace the trade in "thionite", a mind-altering drug, from the source to the end user, they find the different leads all coming together, and all leading straight to the corrupt political machine that was then running North America.While following the leads, the Lensmen visit alien planets and encounter bizarre life forms (and attempt to recruit representative members of as many species as possible as Lensmen).They build a fleet uniting all the continental fleets of Tellus (Earth) into the “Grand Fleet of the Galactic Patrol”, and engage in a massive space battle in defense of their headquarters, “The Hill”.