Sidney can feel her career slipping down the plughole. No one loves a pop star when she's 40 – not if she isn't Madonna or Kylie. So unless she wants to join the ranks of the has-beens on the casino circuit, she better get herself a hit. But what if she regains the whole world and still feels that something's missing? Returning to the feisty mood of her hit The Female of the Species, Joanna Murray-Smith in Rockabye gives our self-involved, celebrity-obsessed culture a satirical duff-up.