Montreal choreographer Edouard Lock, who formed his company under the name Lock-Danseurs in 1980, gained an international reputation in 1985 with the Bessie-winning Human Sex. But U.S. audiences have had few opportunities to see his groundbreaking choreography, a combination of modern and pointe dance that doesn't really fit any of the usual categories. Amelia--the evening-length piece La La La Human Steps is performing here, premiered in Prague in 2002--is said to be based on an encounter Lock had with a transvestite 25 years ago. Reportedly it impressed him with the theatrical potential of everyday life, but that isn't obvious from the excerpts I watched on tape--little was. The piece opens with the projected image of a dancer whose eerily pronounced blinking recalls the cinematography of silent films. In the live dancing that follows, men and women confront each other with quick, wild motions of the arms projecting from a stable torso; the effect is of heated conversation between marionettes. From a technical standpoint the choreography is devilishly difficult--a dancer on pointe kicks a flexed foot high, for example, without disrupting her line or losing her balance. A dancer from the Paris Opera Ballet remarked in an interview that Lock "gives you a position, then superimposes another, then again on top of that, and it is the speed of the transposition that interests him....The danger of course is that you can easily trip up as it all happens so fast." The chiaroscuro look of John Munro's lighting is crucial to Amelia's effect, highlighting the sinews and taut muscles of dancers on pointe. Physically demanding and emotionally acerbic, Amelia may not suit all tastes, but it does seem unique. Joan W. and Irving B. Harris Theater for Music and Dance, 205 E. Randolph, 773-722-5463 or 312-902-1500. Through November 22: Friday-Saturday, 8 PM. $15-$45.