Hamilton, Swan and Klein send Superman and Batman into Kandor for World’s Finest 143 (June 1964).
Batman gets shot while stopping a crime, and sinks into a depression. Superman and Robin come up with a plan to get him out of his funk. Superman, in conjunction with some of his Kandorian friends, fake an attack by metalloids in the bottle city, and request Batman to help. Ace, the Bathound appears briefly in this story, the final appearance of the faithful dog.
Superman and Jimmy Olsen don their Nightwing and Flamebird costumes while in Kandor. Jimmy came along because. He just. Nightwing and Flamebird! Oh, and Nighthound, a telepathic Kryptonian dog that Jimmy had worked with in his own book makes his last appearance here as well.
We also see Nor-Kann, and old friend of Jor-El and Lara, who appeared occasionally in Superman stories from this time. He provides Batman and Robin with flight belts, making them a bit more “powerful” that Superman in his Nightwing guise.
Things get complicated when Batman finds out he has been conned, but then the metalloids turn out to be real, and a sulky Batman refuses to believe Superman. Aside from Batman’s completely out-of-character behavoiur from beginning to end, this story does give everyone a fun role in the adventure, and is miles above the Dictator of Krypton City story, the first time Superman and Batman had a tale set in Kandor.