Written by Lisa Diana Shapiro, with a pop-flavored score by Georgia Stitt, this wry new family musical begins at summer camp, where the title character isn't an ace investigator but an ace nerd. But the "Maltball Falcon" intended for the camp's theater production has gone missing, and you don't have to be a detective to figure out that Samantha will solve this mystery, as well as the noir-ish one that unfolds simultaneously in her fantasies. Deftly explaining its 1940s and '50s references as it entertains, this appealing show offers a soft, tongue-in-cheek version of a hard-boiled genre (1:00).