In the hands of composer/free-jazz high priest William Parker, the double bass moves from its position as rumbling, rhythmic backdrop to an elegant lead instrument through which he's led groups costarring a Murderers' Row of like-minded lions of the avant-garde.

"If the music is happening on a high level, things will fall into place," says Parker. "We practice to allow the music to flow through us."

Next week, with drummer/composer Muhammad Ali, a rotating cast of local free-jazz acolytes, and an all-Philadelphian chamber ensemble, Parker will present an Ars Nova Workshop-commissioned four-piece suite, Flower in a Stained Glass Window (for creative music ensemble and improvising trio), and will play other sets as a trio. The improvisers will, on separate nights, include Philadelphia pianist Dave Burrell and saxophonists Marshall Allen, Bobby Zankel, and Odean Pope. The chamber ensemble, led by Keir Neuringer, will play from charts by Parker.

The suite is inspired by the Frank Furness-designed First Unitarian Church of Philadelphia on Chestnut Street. The group will play in the side chapel of the church next week. At that church, a young Martin Luther King Jr., then a seminary student in Chester, was inspired by lectures on how Mohandas K. Gandhi integrated Thoreau's theory of nonviolent civil disobedience into his own political practices. The performance promises to be awe-inspiring.

Parker was familiar with his friend Ali's gig as drummer with the classic Frank Wright quartet, which was based in Paris in the late '60s. "I didn't really begin playing with him until August 2009, when he subbed for his brother, the late brother Rashied, with whom I played," says Parker. "We also played together in the last version of the David S. Ware Quartet.

"He has a flow and concentration that somehow taps into the essence of the music, blending rhythm, melody, and tone with a kinetic energy," Parker says. "That comes out of the drum tradition, which Muhammad is very familiar with. What I share with Mo is that he is an original and not a copy."

The suite was the idea of concert producer Mark Christman. Of the Martin Luther King connection, Parker says: "I imagined a young King as a living flower, looking through a stained-glass window, hearing words that would mean something to him for the rest of his life."

From there, Parker details each part of the suite he'll present on each night of his four-night stand:

"A Choir," with soloist Pope. The title refers to "the gathering of those needed to sing the message through their lives, participate in boycotts, protest, make a stance."

"The Dream," with soloist Marshall Allen. This section embraces "falling asleep and dreaming about freedom, justice, truth, virtue, as well as dreaming about the mothers and fathers who have died or those who have been lynched."

"The Resistance and Hope" section, with Dave Burrell, which encompasses the power of King's speeches and the harsh aspects of the civil rights struggle, "the anger brought on by injustice and arrogance."

"Unity Forever," with Zankel. "This last section is a cry for unity inspired by Malcolm X, who had come to the conclusion that in order for any freedom movement to succeed, all of the organizations had to be unified.

"Freedom is a shout," says Parker. "Hope is always proudly present in the music and in the eyes of the children."

The William Parker/Muhammad Ali Duo and guests play 8 p.m. Sunday through Wednesday at the side chapel of the First Unitarian Church, 2125 Chestnut St. Tickets $25. Information: www.arsnovaworkshop and www.philauu.org