After distinguished careers in China's state-run orchestras, four musicians retire to enjoy family life and the relative freedoms of the 21st century. But the prospect of one last - and independent - concert reunites them and calls them back to the stage. This is more than a farewell to the music they love; it is their chance to pass it on, renewed, to a wider audience. As the event draws near, a sudden tragedy compels them to reflect on their shared past - five decades of remarkable music that has kept them going through hardship and upheaval.