Cosima has spent all her life at the Home for Unfortunate Girls, along with her best friends: Pearl, Mary and Diya. Cos longs for a real home and a real family.

But when Cos finds out that famed explorer Lord Francis Fitzroy is planning to adopt them, she and her friends know something suspicious is afoot – and they make a plan. They’re going to steal Fitzroy’s prized tiara, containing the legendary Star Diamond of India! But as the big day draws closer, Cos stumbles across a mysterious treasure map that might just reveal the one secret she’s always wanted to know – the truth about her parents