In 1910s San Francisco, concert violinist Roger Grant (Tyrone Power), also known as Alexander, abandons classical music to join a ragtime band with pianist Charlie Dwyer (Don Ameche) and singer Stella Kirby (Alice Faye). Alexander's switch dismays his high society family. As two decades pass and popular music transitions from ragtime to jazz, the ragtime band trio grows both stronger and weaker through love, breakups and war -- all along the rising and falling tide of their musical success.