Back for the third summer in the Hamptons, Mara, Eliza and Jaqcui are determined to make it their best ever. Mara is living with Ryan Perry on his parents yacht, Eliza has her dream job of working for a famous fashion designer, and Jacqui is just ready for a relaxing summer before heading off to NYU.

Unfortunately for the girls, things don't go quite to plan! Ryan turns out to be a world class slob, Eliza gets fired on her first day, by a woman who seems entirely too close to Jeremy, and Jacqui doesn't get into NYU. Can the girls find a way to keep their promise of it being the best summer of their lives?