A spacecraft carrying an atomic device much more powerful than a hydrogen bomb approaches Earth. The World Space Patrol sends Fireball XL-5, piloted by Steve Zodiac, to intercept. It turns out the spacecraft is manned and is carrying out a suicide mission. Zodiac destroys the spacecraft and is instructed to travel to the craft's source -- Planet 46.—Bill Koenig
While dodging a runaway planet out of its orbit, the crew of Fireball XL5 discovers it is on a crash course to the planet Membrono. Assuming the planet is deserted before the crash, Steve discovers after seeing a flying saucer that this planet needs help to avoid the fatal impact...
A duo of wacky aliens, the Lilispatians, captures the commander of XL-7 for hostage to trap the upcoming "Mayflower 3" immigrant spaceship, in order to turn the occupants into slaves for their planet.—RealLiveClaude