(Adventure 064, 1941)
The Unseen Man, aside from his pretty great name, is fairly run-of-the-mill: an art supply owner or employee who somehow develops an invisibility paint, he subsequently turns to crime and is captured by the Sandman.
The reason that the Unseen Man gets such short shrift is that a lot of story real estate is taken up with a subplot of Dian Belmont wanting to be in on the adventure and generally getting in the way, despite discovering at least one key clue. It's all fairly depressing, especially as her earlier, hypercompetent self was still showing up only a few issues prior and she mostly gets pushed out by Sandy the Golden Boy going forward.
Anyway, a shame that the Unseen Man didn't get more to do.
