[1] This particular story line has been lauded as being among the best young adult literature of 1967, ranking among (un-illustrated) novels like Taran Wanderer and The Outsiders.
[2] At their headquarters in the 30th century, five members of the Legion of Super-Heroes watch a Science Police documentary on its most wanted villains, who have been dubbed the "Fatal Five": the Persuader, a paid assassin and enforcer whose Atomic Axe can slice any type of matter or energy; Tharok, a cyborg criminal mastermind; the Emerald Empress, who seized control of the planet Vengar after stealing the mystical Emerald Eye of Ekron;[3] Validus, a powerful gigantic creature who projects mental lightning from his brain; and Mano, a mutant who destroyed his home planet Angtu with the energy that emanates from his right hand.
Short-handed and unable to recruit assistance from other heroes in the galaxy, the five Legionnaires decide to seek aid from the Fatal Five, who would also die if the Sun-Eater cannot be stopped.
Superboy rescues the Emerald Empress as she is about to be executed on the planet Craggok; she accompanies him, bringing a small chunk of green kryptonite with her.
Since Tharok had no time to build a propulsion device, one of them must carry the bomb to the core and detonate it manually, killing themself in the process.
Unable to recover Ferro Lad's remains, the team sends a missile in memoriam to him to the cemetery planet Shanghalla.
In post-Zero Hour continuity, a faction of the Legion is stranded in the 20th century, and the Sun-Eater approaches Earth in that era.
In 2007, the story arc was adapted as "Sundown", the two-part season one finale of the animated series Legion of Super Heroes.