When twelve-year-olds Kat Steiner and Blake ONeill meet at Camp Chickawah, they have an instant connection. But everything falls apart when they learn theyre not just best friendstheyre also half sisters. Confused and betrayed, the girls break off all contact.

Fifteen years later, when their father dies suddenly, Kat and Blake discover hes left them a joint inheritance: the family beach house in Destin, Florida. The two sisters are immediately at odds. Blake, who has recently been demoted from regular nanny todognanny, wants to sell the house, while social media influencer Kat is desperate to hold on to the place where she lived so many happy memories.

Kat and Blake reluctantly join forces to renovate the dilapidated house, with the understanding that Kat will try to buy Blake out at the end of the summer. The women clash as Blakes renovation plans conflict with Kats creative vision; meanwhile, each sister finds herself drawn into a summer romance. As the weeks pass, the two women realize the most difficult project they face this summer will be coming to grips with their shared pastand learning how to become sisters.