Ghost of John McCain, the Off Broadway musical comedy that sent Meghan McCain into a summer-long pre-opening tizzy, has arrived after months of free publicity.

A modestly entertaining, fitfully clever political satire that takes place entirely within the frazzled head of Donald Trump, a place that looks a lot like a three-star hotel lobby populated by the likes of, among others, the late Arizona senator, Hillary Clinton, Eva Peron, Taylor Swift, Joe Biden, Lindsey Graham and a Melania-Ivanka mash-up referred to simply as Daughter-Wife.

Ghost of John McCain ultimately comes off as a nicely performed, conceptually overcooked 90-minute SNL cold open set to an amiably cartoonish show tune score.

With a book by Scott Elmegreen, a score by Drew Fornarola and direction by Catie Davis, Ghost of John McCain was co-conceived by McCain’s first chief of staff Grant Woods, and a gentle affection for the “Maverick” underlines the entire...