Eighteen years ago Martha said goodbye to best friend Juliet on a moonlit London towpath. The next morning Juliet's bike was found abandoned at the waterside. She was never seen again. Nearly two decades later Martha is a TV celebrity, preparing to host a new crime show... and the first case will be that of missing student Juliet Sherman. After all these years Martha must reach out to old friends and try to piece together the final moments of Juliet's life. But what happens when your perfect friends turn out to be perfect strangers...?