You do have a knack for stating the obvious! 
Green Lantern (Volume 2) #123 is an issue of the series Green Lantern (Volume 2) with a cover date of December, 1979. It was published on September 27, 1979.
Synopsis for "Mission of No Return"
Guy Gardner is trapped in the Phantom Zone and is being controlled by three exiled Kryptonians including General Zod.
Green Lantern goes to Superman's Fortress of Solitude where Superman sends him (and a lead case) into the Phantom Zone. The Kryptonians can focus their wills through Guy and control his ring, but Green Lantern opens his case revealing Anti-Kryptonite which is deadly to the phantoms. A yellow beam of light pulls Guy away. Green Lantern takes the Anti-Kryptonite and leaves. He deduces that Sinestro was behind Guy's disappearance.
Green Lantern has a quick argument with Green Arrow and goes home to recharge his ring where Kari finds him. Hal left Kari at the altar but she realizes he is leaving to rescue her other love, Guy, and wishes him well.
Green Lantern finds a one-way portal into Qward. He waits for Sinestro to appear but Guy appears first. Scanning him, Green Lantern discovers Guy is being controlled by Sinestro. The two fight, but Sinestro gets the upper hand by encasing Guy in a yellow bubble which he slowly contracts. He promises to stop once Green Lantern gives up his power ring. Stalling for time, Green Lantern asks to make sure Guy is still alive. He realizes that the space in Qward is not airless. He quickly zaps numerous planetoids, turning them to dust, then creates a fan to blow the dust in Sinestro's face. Sinestro becomes temporarily blinded and Green Lantern attacks. Guy, drifting towards rocks, calls for help. Green Lantern rescues him during which Sinestro escapes. Guy is taken to Mercy Memorial Hospital where the doctor says he's never encountered this time of brain damage before. Kari arrives to take care of him and Green Lantern vows to continue searching for Sinestro.
Appearing in "Mission of No Return"
Featured Characters:
Supporting Characters:
Antagonists:
Other Characters:
- Kari Limbo
- Superman
- Doctor Bentley (Single appearance)
Locations:
- Phantom Zone
- Qward
- Earth
- North Pole
- Star City
- Oliver Queen's place
- Coast City
- Hal Jordan's place
- Mercy Memorial Hospital
Items:
- Anti-Kryptonite
- Green Lantern Power Battery
- Green Lantern Ring
- Phantom Zone Projector
- Yellow Lantern Ring
Notes
- Starting this issue, the series returns to Green Lantern solo adventures. Series was previously titled Green Lantern and Green Arrow.
- Hal mentions the channel that leads to Qward is permanently sealed on the Qward side (i.e. it's a one-way portal). It is not explained how he returns to the positive universe.
- Guy Gardner ends in a catatonic state in this issue. His next appearance is in Tales of the Green Lantern Corps #3, but he doesn't fully recover until Green Lantern (Volume 2) #193.
See Also
Recommended Reading
- Green Lantern Recommended Reading
- Green Lantern (Volume 1)
- Green Lantern (Volume 2)
- Green Lantern (Volume 3)
- Green Lantern (Volume 4)
- Green Lantern (Volume 5)
- Green Lantern (Volume 6)
- Green Lantern (Volume 7)
- The Green Lantern (Volume 1)
- The Green Lantern: Season Two (Volume 1)
- Green Lantern Corps (Volume 1)
- Green Lantern Corps (Volume 2)
- Green Lantern Corps (Volume 3)
- Green Lantern: Emerald Warriors (Volume 1)
- Green Lantern: New Guardians (Volume 1)
- Green Lanterns (Volume 1)
- Hal Jordan and the Green Lantern Corps (Volume 1)