Liza Pehrson, center, and other cast members, rehearse the opening scene of the play Opus. The play follows a world class string quartet that has to adjust to to a new, talented member days before a televised performance at the White House.

“Opus,” a play by Michael Hollinger that opens at Theatre Lawrence tonight, is written like the complex piece of music from which it draws its name says director Doug Weaver.

“In essence, it’s a four-part harmony,” Weaver says. “Four different notes making music together.”

Here, the “notes” are the principle cast members. The plot follows a world-class string quartet that hires a young, less-experienced player to replace a member who has been fired mere days before the group is scheduled to give a concert at the White House that will be broadcast on national TV.

Charles Goolsby, left, and Liza Pehrson rehearse a scene from Opus. The play follows a world class string quartet that has just fired one of its members and is struggling to adjust to its talented new musician days before a televised performance at the White House.

Tensions rise in the rehearsal room, and, on several occasions, the four musicians argue and bicker — sometimes in four-part, disfunctional harmony.

“There are about four arguments where it’s like a musical composition,” Weaver says. “The rest of the time it’s more about human interaction.”

Each of the characters have a distinct voice and personality that echoes the tone of their instruments, Weaver explains.

The cello player has a deep voice and “is quiet and taciturn,” Weaver says. While the viola is the high pitch instigator. “The second violin is the second highest” in pitch, “the person who plays all the notes. And the first violin is the genius, the virtuoso.”

The play was one of the most challenging Weaver has directed, he says, because not only did the timing and story tension have to be right, it also had to sound right.

“We cast the characters to make sure their voices sounded right,” Weaver says.

For example, Weaver asked Charles Goolsby, who plays the first violin character, to talk in the top register of his voice. Likewise, Weaver directed Randy Parker, who played the cello player, to speak on the low end of his register.

Weaver was reluctant to take on the play, because he had just finished directing “Shout” for Theatre Lawrence when he was offered the job. “But then I read it,” he says, “and I was bowled over.

Liza Pehrson, rehearses a scene from the play Opus as director Doug Weaver watches in the background.

“It’s about trying to make art while being human,” he adds. “These characters are probably the best players in the world, but they make incredibly human mistakes. They’re petty, jealous, and just in so many ways like the rest of us. Yet, at the same time, they’re trying to achieve this almost nirvana-like perfection.”

As challenges go, Weaver says “Opus” was one of the biggest he’s experienced as a director.

“I do a lot of plays all over the country, but this one was tough,” he says. “But I was helped immensely by a playwright where theatre needs to be, and a very strong cast.”

He also got help from area musicians. Steve Donaldson, executive director of the Lawrence Chamber Orchestra gave advice, and Richard Walker, music director for the Lawrence Art Center Voices choir, served as music director for the play.

Thought the characters in Opus world class musicians, the actors understandably, are not. Director Doug Weaver brought in Steve Donaldson, executive director of the Lawrence Chamber Orchestra, to advise the actors and Richard Walker, music director for the Lawrence Art Center Voices choir, served as music director for the play.

“He showed the actors how to hold their instruments so that it looks like they know how to play,” Weaver says.

And he helped Weaver think more like a musician as he directed the play.

Walker has “forgotten more about music than I’ll ever know,” Weaver says.