WE WERE LIARS BY E. LOCKHART

The book begins with a story told by Cadence Sinclair, the book's protagonist. She talks about her life and her summers, before Summer Fifteen, that she spent on a private island, owned by her grandparents. The island, which is near Martha's Vineyard, has four houses for each child and their family. and staff facilities. She then tells how she got to know an Indian boy named Gat and how she fell deeply in love with him.

In Summer Fifteen (as in the fifteenth year Cadence has spent the summer on the island) they have a relationship, but they reach a rocky road when the accident happens. Cadence is found seriously injured in the water, near the beach. She suffers migraines since then and is not able to remember much of Summer Fifteen except details of her accident. Even with this information, her mother refuses to disclose what happened in Summer Fifteen. Because of the accident, Cadence is held back one year and retakes her classes, but in constant pain and as a significantly different person.

In Summer Sixteen, Cadence is told by her mother that she will be travelling Europe with her father. Despite resisting, Cadence goes on the trip; next Summer, she returns to the island.

When she does return, just about everything on the island is different. Everyone, including the Liars, (the cousins and good friends of Cadence who also go to the island) acts nervously and secretively around Cadence; and one of the houses on the island is remodeled to a modern, sleeker aesthetic. Over time, Cadence remembers more and more about Summer Fifteen and her relationship with Gat. She eventually remembers that her family and her extended family were arguing over who gets the inheritance. She also remembers that her grandfather towards Gat and his uncle (implied from how he reacted to Gat and Cadence kissing in an attic in one of the houses; and how he acted toward's Gat's uncle marrying a family member).

Towards the end of the book, Cadence remembers what happened during Summer Fifteen. While drinking wine, the Liars drunkenly plan to stop their families from tearing each other apart by burning down one of their grandfather's house using gasoline from the boat house. The plan was to soak a number of objects around the house in gasoline, soak the second floor in gasoline, light the second floor on fire using paper towels, and then light the first floor on fire. However, the plan quickly goes awry as Cadence lights the living room on fire first. This traps and kills the family dogs, and the Liars. Suffering from burns gained from escaping the fire, Cadence dives into the water in her underwear, explaining why she was in the water earlier in the book. Upon this realization, she quickly realizes that the Liars were "ghosts", formed out of Cadence's guilt. She comes to terms with the Liars one-by-one and with Gat. The book ends with Cadence significantly better than she was after her injuries sustained Summer Fifteen.