“Frantz meets Swanilda. Frantz and Swanilda fall in love. Then Frantz meets Coppélia.” That’s the deceptively simple plot of the ballet “Coppélia,” which, with a score by Léo Delibes, made its debut in 1870 in Paris. The catch is that though Frantz thinks Coppélia is a living doll, he’s only half right: she’s the mechanical creation of Dr. Coppélius. Before it’s all over, Swanilda, caught snooping in Coppélius’s workshop, has to pretend to be Coppélia, so in a sense the doll does come to life. This is the most light-hearted (though never lightweight) ballet in the classical repertory, and the 1974 George Balanchine version that Boston Ballet has just opened at the Boston Opera House is engaging throughout, with high-spirited performances Thursday night from a boyish Jeffrey Cirio as Frantz and a unnervingly doll-like Misa Kuranaga as Swanilda.
What is particularly nice about Balanchine’s “Coppélia” is that it preserves the original third act, which some companies, such as Paris Opera Ballet, have dropped. The plot — which, like the Olimpia segment of Offenbach’s “Tales of Hoffmann,” is freely based on E.T.A. Hoffmann’s 1816 story “The Sandman” — unfolds in the first two acts; the third, like the finales of “The Sleeping Beauty” and “The Nutcracker,” is a set of divertissements followed by a pas de deux for the reunited Frantz and Swanilda. Two dozen student girls dance Delibes’s lilting “Waltz of the Golden Hours,” a typical village day’s activities are depicted by ballerinas representing Dawn, Prayer, and Work, Discord and War intervene, and then the pas de deux restores peace.