POP REVIEW Bob Weir and Hanson: Teen-Age Idols Come Alive at a Temple for Deadheads By ANN POWERS

NEW YORK -- The truth behind a pop conspiracy was unveiled late Saturday night at Wetlands during the second night of Bob Weir and Rob Wasserman's three-night stand. After midnight Weir, the Grateful Dead guitarist, and his stand-up bass-playing collaborator stepped back onstage to continue their jam session, and Weir announced that he had some friends to welcome.

Out bounded three rosy teen-agers in blond ponytails who sped into a spirited set of blues oldies and Dead tunes, led by an enlivened Weir. Yes, it was Hanson, the fraternal team behind "MMMBop," revealing itself to be not a teeny-bop act after all, but a hippie reconnaissance unit spreading the Dead's legacy to a new generation.

All right, the conspiracy bit is a bit far-fetched, but Isaac, Zachary and Taylor Hanson were obviously overjoyed to be playing music more funky and expansive than what their usual fan base of 10-year-olds demands. Weir also gained a spark from the exchange, letting loose his most intense guitar leads of the night and even attempting a Little Richard-style scream on the final song, "Another Saturday Night."

Although he graciously let Isaac take a couple of competent guitar solos, his attention gravitated toward the keyboard-thumping Taylor, the most precocious brother and the only one wearing tie-dye.

The audience resisted hysterics at the sight of the teen idols; many fans didn't even seem to know who they were at first, and they'd already spent their idol-worshiping energy on Weir himself.

This appearance, his first New York club date in a quarter-century, celebrated Wetlands' 10th anniversary. Since the club was founded as a gathering place for those mellow obsessives known as Deadheads, Weir's presence has had the effect of a holy visitation. Luckily, because the trio he has formed with Wasserman and the drummer Jay Lane is so supple and intuitively connected, it also made for very fine music.

The set included several Bob Dylan compositions, a couple of excellent oldies (including a genteel take on "Twilight Time," which suited Weir's patrician singing style), and the requisite Dead sing-alongs. Wasserman and Lane both took song-length solos, with Wasserman showing his improvisatory chops by responding to an audience request by playing an emphatic version of "I Can't Get No Satisfaction." Mostly the three men intertwined their efforts in the casually dynamic style for which the Dead was known.

Another surprise came when Hun-Huur-Tu, the throat-singing group from Tuva, stopped by after its Town Hall performance.

These Siberian artists, known for producing multi-note harmonics by manipulating their vocal cords, performed a few songs with commentary provided by a translator.

One member played electric guitar on the final number. The music did not seem to betray any link to either Hanson or the Grateful Dead, but who knows? Perhaps this conspiracy reaches farther than anyone suspects.