SERENADE: Warning signals, disappearing dancers.

It’s a good pairing: together, Serenade and La Sylphide write an essay on doomed love. Serenade sends out warning signals from its opening tableau — 17 women all with right arm extended and hand flexed — and yet by the end of Tchaikovsky’s sportive Sonatina, a man and a woman have hooked up. They gambol in the Waltz that follows (hence their usual casting names, Waltz Boy and Waltz Girl) and in the jaunty Tema Russo. Meanwhile, Russian Girl (another casting designation) comes and goes, at first blessing the couple, then joining a quartet of women who appear to spin out the pair’s fate. At the end of the Tema Russo, Waltz Boy runs out — or off — with the 16 women while Waltz Girl crashes to the floor. Two (afterlife?) figures appear: Elegy Man and, her hand over his eyes and heart, Dark Angel. Russian Girl enters and the four of them dance, à la Balanchine’s Apollo, the three women with their hair down; after a bit, Russian Girl, like Waltz Boy, disappears, Elegy Man and Dark Angel move on, and Waltz Girl is comforted by some of the women and and borne aloft by three men — into the Light? — as the curtain descends..

La Sylphide is easier to follow but not less complicated. We’re in the Scottish Highlands, and James seems set to marry Effie, despite the efforts of her other suitor, Gurn. But as the curtain rises, the Sylphide — a winged woodland sprite — appears and makes her love known to James. World or otherworld? Prose or poetry? And there’s a third woman in the picture: old hag/witch Madge. (Like Serenade, La Sylphide is a story of two men and three women.) Madge slips into James’s castle to get warm; he fears she’s a bad omen and orders her out; she vows revenge. It’s Madge’s poisoned shawl (act two, echoing the plot and the psychology of Macbeth, opens with a cauldron scene) that James wraps around the Sylphide and that causes her death. But is it Madge’s fault that James wants the Sylphide and sex? Or is Madge the Loathly Damsel of British folklore who’d have turned into the Princess if he’d wanted her? Effie weds Gurn, James swoons as the body of the Sylphide is born aloft, and Madge mocks him. You wonder whether his story, like Waltz Girl’s, is just beginning.

The highlight of the four performances I saw last weekend was Melanie Atkins. Her Russian Girl breathes Balanchine, her inscrutable smile suggesting she’s in communication with Mr. B, her long limbs flying, her pelvis centering, her body dangerously tilted. On her two entrances in the Elegy, she gave the audience an unnerving half-look, as if bearing news from Delphi. To Madge, she brought not only a convincing arthritic limp but the kaleidoscopery of her Balanchine — right down to the “Ahh . . . 15-year-old Laphroaig” expression after downing that first Scotch. This Madge might want James for herself: she keeps thrusting beauty in his way and he doesn’t see it. Atkins capped off her weekend Saturday afternoon with a delectable turn as the solo sylph.