Dublin schoolgirl Rosie McGrath may be only thirteen and a half, but she has seen more of life than either her parents or teachers realise. When her art teacher Ms Henry discovers a painting in the National Gallery with an uncanny resemblance to the teenager and shows it to her, she inadvertently sends Rosie off on her last adventure – into 1963 to find the painting’s artist Jennie O’Neill. Suddenly Rosie is thrust into the world of St Catherine’s boarding school where Mother Misericordia rules with an iron will, girls have to recite 30-verse poems and shoes are pointy and uncomfortable. Where’s the freedom and cool music her mother’s always talking about? Rosie thinks the 60s are seriously sad. And Rosie has a battle on her hands – to stop the evil Stacia Bolger’s plot to get Jennie expelled, find something that’s been missing for 10 years and introduce the other teenage girls to modern day essentials – boys and parties.