Back in Brittany, Captain Morgane Ledantec is confronted with the discovery of human bones after the fall of a sacred oak during a storm. The victim was a follower of druidism which Morgane was introduced to as a teenager by her godmother.
Alex, whose singing career can't manage to succeed, accepts a strange job : to make a pensionner choir sing nursery rhymes. She finds out a bunch of out of control old people who dream of singing rock and roll music ! Her mission will be more complicated than expected...