The P-1 was sent to explore the newly-discovered Planet X, located just beyond Jupiter. When the ship arrived, its two pilots, Glenn and Fuji, were brought to the underground lair of the Xiliens, an advanced alien race who lived on the planet. After a talk with them, they returned to the ship to contact Earth about bringing Godzilla and Rodan. Once they were at the planet, the P-1 was remade by the Xiliens with an extra seat, so that Fuji could act as a co-pilot. The P-1 returned to Earth, where it was later destroyed by the Xiliens as one of the Xilien UFOs rocketed past.