Sycamore Hill Boarding School,Donegal, 1963

Clare Rose and Molly are happy to be back at Sycamore Hill, getting ready for the school musical and training hard at hockey. When new girl Amy joins their class in the middle of term, she's a bit of a puzzle to solve. Amy's vague about her home and is never allowed leave the school grounds with the other girls. Clare wonders if she's a film star or millionaire in disguise!

But then a new nun unexpectedly joins the staff and Clare and friends begin to fear Amy's secret is something darker. Could Sr Eva be there to spy on Amy – or harm her? Who can the girls trust?

Clare, Rose and Molly vow to use their detective skills to get to the bottom of this new mystery before it's too late.