Annie Andrews and her sister Isla are the best of friends but two very different souls. They are raised in the Scottish Highlands by their very conservative parents. Annie is a wild child while Isla is sensitive and responsible. When Isla is 10, Annie wakes her up to tell her she is pregnant. Their parents set Annie and her newborn son Callum in a flat above the gift shop they own, telling her she must face her consequences and raise her child on her own. For 11 years, Annie and Callum happily live in Inverary, above the gift shop, until one girl’s weekend, Annie meets the diminutive Dom and falls in love almost instantly. Dom is there with his friends Gavin and Tom. While they live far apart, they continue to correspond with letters. Isla, being the more sensible, warns Annie that they are moving too fast, but Annie is swayed by his charm and is swept away. Within two years, Dom and Annie marry, and she has moved with Callum to their charming new home in Dorset, where Dom runs his family business.
Over a decade later, Isla receives a frantic call from her nephew Callum, now 20. Annie and Dom are dead, murdered, and then Annie’s beloved studio set on fire. Isla leaves at once so she can support Callum and find out what happened. But when she arrives, she realizes the Dorset police only have one suspect, her beloved nephew. As Isla navigates what has happened, she learns of all the secrets Annie kept from her, including Dom’s abuse, cheating and his treatment of Callum. She must now face that Annie was not who she thought her sister was and reconcile that she did not know her as well as she thought she did.
S.E. Lynes does a spectacular job portraying a marriage entrenched in abuse and secrets. Dom, with his Napoleon syndrome, is a spoiled bully. Annie, so certain she has found her happily ever after, exhausts herself trying to hide the abuse she is suffering, while carving out a life for herself in the small town. All the promises Dom has made to her turn to dust, and he becomes so cruel that your heart will break for Annie as her dreams also turn to dust. But who is really to blame? What happened that night in Annie’s art studio that burned to the ground?
When Callum is arrested for the murder of his mother, Isla is convinced he is innocent and will do anything to prove it. She knows he would not have killed Annie, as there was no one he was closer to. Over the next few months, as Callum awaits his trial, Isla makes a life for herself in the small town, with the help of Annie’s best friends and Annie’s former lover, Ross.
From the beginning of Her Sister’s Secret to the shocking twist revealed in the final chapters, we find Isla to be a reliable and careful narrator. The story alternates between Annie’s voice to Isla in the present day, often with flashbacks to conversations and experiences they had together. This is one enjoyable story, with just the right amount of tension.