Twelve summers ago: Poppy and Alex meet. They hate each other and are pretty confident they'll never speak again. Eleven summers ago: they're forced to share a ride home from college, and by the end of it, a friendship is formed. And a pact: every year, one vacation together. Ten summers ago: Alex discovers his fear of flying on the way to Vancouver. Poppy holds his hand the whole way. Seven summers ago: they get far too drunk and narrowly avoid getting matching tattoos in New Orleans. Two summers ago: it all goes wrong. This summer: Poppy asks Alex to join her on one last trip. A trip that will determine the rest of their lives.