Deep in Africa Ming locates an anti-energy source enabling him to open the Nightgiant Doorway and unleash 7-story tall nightgiants to destroy the earth. Flash flies out to space to destroy a Ming satellite, but his ship is immoblized by the Merciless One's roboships, while the Phantom goes to Africa to terminate Ming's activities in the Forgotten City. As the nightgiants terrorize various parts of the globe Rick intercepts a transmission from Ming to Garax and discovers that a transport invertor will eliminate the monsters. Mandrake, Lothar, Rick, L.J., Jedda, Kshin and Zuffy take on two nightgiants outside of Central City while racing to the stadium to retrieve the saving invertordevice. As they recover the device, Rick is captured by one of the creatures. Jedda departs for Africa, where her father will use the transport invertor to close the nightgiant doorway, while the other Defenders save Rick. Out in space Flash finally fights off all of Ming's minions and blows the satellite. Jedda delivers the transport invertor to the Phantom and they battle Ming's troops before employing the device and sending the nightgiants back to their own world.