Second Stage Lensmen by E. E. Smith

Earth is once again in peril. The Boskonian organization, thought defeated, has acquired the negasphere technology and is preparing to use it against Earth, destroying it and everyone on it. It is up to Lensman Kimball Kinnison and the four new second stage Lensmen of the Galactic Patrol to stop the Boskonian threat and save civilization. The fifth book in the Lensman series and the sequel to Gary Lensman. - Summary by The Narrator