Mark Morris remains my favorite choreographer working today. There are others who fall a very close second and third, but his work is still the most attentive, the most sublime, the most surprising. In fact, it is that element of surprise that appears, however subtly or unexpectedly, in each of his works that I think I like best. And it is easy to love dancers as clean as those in the Mark Morris Dance Group. They somehow have no affectations, no frills—just clean, beautiful lines.

Though the opening piece Pacific—originally created for San Francisco Ballet in 1995 and new to MMDG—starts off rather woodenly and cautiously, by its end it is rousing, commanding, deliciously free. Lou Harrison’s Trio for Violin, Cello, and Piano is stark but never overpowering. A movement motif in which the dancers luxuriously rond de jambe en l’air a leg only to fouetté it derrière at the last second feels fresh every time it is executed (especially when the stately Laurel Lynch is doing it), just as a swift toss of the arm and torso from an upright position to an angle 45 degrees different does.

Words (which I saw back in October at its Fall for Dance premiere) appears little changed, to its advantage. It is still a charming romp, expertly constructed and danced feelingly. Its moments of surprise—dancers who exit, (largely) unseen, behind a handheld scrim while hopping on one foot; unexpected canons that mirror in costume as well as movement—are perfectly paced. The duet between Aaron Loux and Domingo Estrada remains my favorite section, for its intensity and careful alignment of dance and music.

Grand Duo, which finishes the program, manages to be many different things at once: primitive, ritualistic, quirky, percussive, even sanguine. It’s still easy to recall the indomitable Lauren Grant repetitively chugging her feet as her arms and fingers look as if they’re casting spells in every direction.

Mr. Morris’ world premiere Whelm, sandwiched between Words and Grand Duo, is a piece in which there appears to be a clear narrative, though it is never made explicitly known. This inevitably lends the work an air of mystery, of a puzzle wanting to be solved. Sometimes this can translate all too easily into frustration on the part of an audience member; with Mr. Morris, the reverse is true. Instead of forcing myself to construe a plot, however nonlinear, from the obvious onstage characters and their interactions, I found it easy to observe the goings-on from a noncommittal vantage point. I could examine each new element—one character wears a translucent black veil over her head and slowly traverses an upstage swatch of the stage, conjuring up death and funereal sadness and even, somehow, Russianness—and then let it fold into the back of my mind as the next one (this time, a dancer wearing a dark hood) manifests itself.

The three of Debussy’s études accompanying are nicely evocative and spare. The four dancers slink and slither, on the ground and across each other. Two of them are dressed as if they’re on their way to rob a bank; Maile Okamura’s costume is a bit more chic, with tufts of fur at her wrists and neck. In the piece’s final moment, Dallas McMurray runs upstage and leaps as if to splat himself against a wall—where he is caught by a fifth dancer who has not appeared yet onstage.

I am left mystified but not irritated—which feels wonderful, and ambiguous. Which is probably just how Mr. Morris intends it.