Detective Comics Vol 1, Issue #351

The Cluemaster's Topsy-Turvy Crimes! / The Case of the Costumed-Made Crook
Newsstand Edition
Release date: Feb 24, 1966

Key: the first appearance of Cluemaster

The Cluemaster’s Topsy-Turvy Crimes! A new villain calling himself the Cluemaster hits Gotham with a spree of baffling, brain-teasing crimes that push Batman and Robin to their limits. And the pressure spikes at home, too—Aunt Harriet grows suspicious, putting their secret identities in real jeopardy.

The Case of the Costume-Made Crook When Ralph Dibny’s old Elongated Man uniform is stolen, it’s more than just a burglary—it’s a threat to his reputation. With a ceremony looming to donate the suit to the Flash Museum, Ralph races to track it down before someone else uses it to make headlines for the wrong reasons.