Action Comics #360

In this 1968 installment from Action Comics #360, Supergirl’s powers gone, Linda Danvers faces a new chapter as she prepares to be adopted by the Danvers family. But when Kandorian scientist Lesla-Lar hijacks a teleportation device, she swaps places with the powerless hero—stepping into a role that makes her Lex Luthor’s most dangerous secret weapon.

In "Part 3: Trapped in Kandor!", Supergirl remains powerless after Lesla-Lar's ray, but when Superman brings her into the past, they discover her abilities return in earlier eras—uncovering a strange, time-dependent mystery that could be their only way out.

In "Part 4: The Three Red 'K' Perils!", a powerless Supergirl uses a time machine to journey to a future ruled by the oppressive Clan of Censors, where she regains her powers and helps liberate humanity. Upon returning to the present, she discovers her abilities have returned—and she's now immune to kryptonite—just as the truth behind Lesla-Lar's scheme to replace her in Kandor begins to unravel.

When a Red Kryptonite meteor transforms Supergirl into a mermaid, she finds herself in Atlantis, where Jerro is smitten and proposes—unaware that Lenora, Lori’s sister, is also captivated by him.