The conclusion to the Man-Bat trilogy is in Detective 407 (Jan. 71), by Frank Robbins, Neal Adams and Dick Giordano.
The story picks up from the last Man-Bat tale, with Batman’s attempt to cure Kirk Langstrom. Once again, the crazed Man-Bat flees from Batman.
Kirk returns to Francine, and begs her to go along with his plans. While I loved this story as a kid, and it still reads like a twisted gothic romance, it’s hard to swallow Francine’s extreme submissiveness in this story.
Chiefly, that she agreed to take the serum herself, transforming her into She-Bat. Batman does manage to stop their wedding, but is taken aback when he sees Francine’s change.
Batman does ultimately corner the couple, and injects them both with the antidote.
As with the original Two-Face trilogy, this does bring their story to an end. But the huge popularity of the character ensured his return the following year.