The Mortland girls --- beautiful mean Julia, aloof Finn, and young "different" Maisie --- come with their mother, Stella, to live in their grandfather's home, a huge and ancient ruin of an abbey. Maisie instantly befriends the ghostly nuns who haunt the place and busies herself with the writing of many lists.
In the summer of 1967, family friends Dan, Nick and Lucas arrive for a visit. Lucas is painting the girls' portraits. When he works on Maisie, she entertains him with tales of the family's past. However, when Maisie tells of having her fortune told years ago, he scoffs and so she doesn't tell him what she saw in the fortune teller's crystal ball.
As the family begins to prepare to travel to Gramps's childhood home for their annual visit, their place is enveloped in a brooding sense of impending doom. Maisie (who wanders at night) spies Finn returning home very early in the morning, naked under her dress. Maisie worries that Dan's heart will be broken if Finn has been with Lucas, as she suspects.
Before the family leaves on their trip, Stella and her father work on their plan to ask Gramps's wealthy brother for a loan to repair the crumbling Abbey. Maisie slips away, spying Lucas furtively leaving for Cambridge on Julia's bike. Did he steal it? Maisie then overhears a passionate argument between Dan and Finn, followed by an equally passionate embrace. The house is filled with fear, distrust and despair. Maisie doesn't know what is wrong with her family but decides she must take action to help them.
As usual Gramps's brother rebuffs the family's request for a loan. However, Maisie acquires money through surprising means. During this transaction she learns that her family fears she'll turn out like her deceased father. What on earth does that mean?
The story picks up again in 1989 and becomes Dan's tale rather than Maisie's. The sense of impending doom turns to suspenseful mystery as Dan reflects back on a tragedy that occurred during the summer of 1967 involving the Mortland family. Lucas is now a celebrated artist planning to show his 1967 portrait, The Sisters Mortland, at a retrospective. Dan is horrified at the thought of stirring up the family tragedy and sorrow.<