In “The Marvelous Wonderettes” the 1958 Springfield High School prom — and the 10-year reunion in 1968 — provides the title quartet of choirgirls the opportunity to harmonize to the great hits of those respective eras. You can tell going in that this is pure fluff, strictly intended as entertainment, and on that level it succeeds fairly well.

The hits come non-stop, from “Mister Sandman” to “Son of a Preacher Man” and everything in between, and the singers are terrific with a strong sense of style to match their powerful voices. The crepe-paper-thin plot serves mostly to frame the songs — at best it gives them a bit more oomph, at worst said “plot” is inane nonsense.

It’s all quite contrived, which, given the show’s light-hearted aims, is perfectly fine. At times, however, the show seems cynically calculated, which is less forgivable and dampens the fun. For example, the audience is asked to vote for their favorite girl as prom queen. That seems like a harmlessly amusing way of drawing the audience in and engaging them, right?

Wrong! Those votes are swiftly tossed away, and the prom queen that the plot calls for is promptly crowned. Why did we bother to vote? That borders on contempt for the audience that the creative team otherwise seems so bent on entertaining. That, and a handful of other similar things, isn’t really that big a bummer, but collectively they do mean that “Wonderettes” is merely diverting, rather than the true delight it could so easily have been.

Tickets: www.telecharge.com