Henry stood on top of a boulder pile in Central Park. His fists dug into his hips. He surveyed the New York City landscape in a Superman pose. He dressed as if he were a hipster Clark Kent, with a bomber hat, and a faded X-Men t-shirt underneath a size-too-small sweater. His bare, red fingertips trembled.

“They’ll never suspect us like this!” shouted a voice from below.

That...