Call it the "Red Viola."

A viola once in the possession of Eugene Phillips, former Pittsburgh Symphony Orchestra member and an active composer, has a story nearly as mysterious as the one in the acclaimed film, "The Red Violin." While a composition he wrote for both violas and violins will be the showcase of an 80th birthday celebration this weekend at Pitt, the viola that got away will be a part of it.

In the late 1940s, Phillips had joined the PSO but was studying composition with Nikolai Lopatnikoff at Carnegie Tech. That meant he also had to play in the school orchestra, which needed a violist more than a violinist. Phillips could play both, so he obliged. His father, instrument builder and performer Benjamin Phillips, made one especially for him with a body length of 16⁵/₈ inches.

"It was an unusual size," says Eugene, who lives in Squirrel Hill with his wife, Natalie, a respected local piano teacher. While violins have a standard full size, violas come in various dimensions. The unusual size of Phillips' viola would later prove crucial after one fateful rehearsal. "At Carnegie, everyone just left their instruments on a long table in the hallway and we went out for a smoke," he said. "When I came back in, that viola was gone. We even had a detective look for it."

The viola was never recovered, and his father eventually built another one for him. All was quiet for decades until two years ago.

"Someone called me from Chicago, a guy who had played viola in the Grant Park Orchestra for 40 years," he says. "He was retiring and wanted to sell a Benjamin Phillips viola." Eugene didn't think much of it at first. His father had made many instruments. Then he asked about the size. "16 five-eighths," came the reply from the seller, who said he had bought it from his teacher in Florida, who in turn had bought it in Washington, D.C. years ago. "At that point I had an idea it could be the lost viola, but I hadn't seen it," says Phillips.

He knew his son, Daniel Phillips, who with other son, Todd, are the violinists of the renowned Orion String Quartet, was looking for a new viola. The Chicago musician sent it to Daniel, who bought it. "I didn't see it until I visited New York," said Eugene. "This viola had some special marks in the wood and I recognized it immediately. Danny has it now. After 55 years it finally came back into the family."

Phillips played both violin and viola throughout his career, including his service in an Army radio band during World War II (that also toured the area selling war bonds and visiting hospitals) and his tenure with the PSO. He joined under Reiner in 1947 as a violist, was then moved into the first violin section. He left the PSO to teach only to rejoin it in 1966 -- originally as a violist until William Steinberg switched him back to the first violins.

So it is fitting that Phillips would write a piece that shuffles the two instruments. Dedicated to his two sons and Todd's wife, violinist Catherine Cho, "Trio for Three" asks the three performers to play both instruments at various times.

The first movement is for three violins, the second for two violins and one viola, the third one violin and two violas and the finale for three violas. "The instruments lie on a table behind them," says Phillips. "As soon as one person is done playing on the violin [he or she] turns and picks up a viola." When Daniel, Todd and Catherine perform it this weekend, they will play on Benjamin Phillips violas and violins.

And that "red" viola? Todd will play it during the performance. Even Hollywood struggles to ties ups plots that neatly.