Two rival marine biologists, an extremely small boat... and one very big lie. Andi has learned to love her predictable life in Ohio. But when her marine biologist sister needs emergency surgery, Andi agrees to take Millie's place on the trip of a lifetime: scuba diving on the Great Barrier Reef. There's just one problem: Andi must pretend to be Millie the entire time. But when Andi arrives in Cairns, she is horrified to learn that Hugh Harris - Millie's professional rival and extremely vocal social media critic - is also on-board. And he's very handsome. Perfect. Somewhere between the sunsets and the beauty of the underwater world, Andi begins to question the mundanity of her life at home and whether she is capable of being the woman Hugh believes her to be. But how can you truly fall for someone when they think you are someone else?