The Rolling Stones are still rocking, drawing huge crowds to concerts.
But today's band lacks a key figure from its early days: guitarist Brian Jones.
Jones died in 1969, shortly after the other founding members kicked him out of the Stones.
His large musical contributions to the shaping of the band and his bumpy personal life are detailed in Paul Trynka's book Brian Jones: The Making of the Rolling Stones.
Trynka joins us from England to talk about his book and the research into it.