Thirteen-year-old Ellen Katz feels most comfortable when her life is well planned out and people fit neatly into her predefined categories. She attends temple with Abba and Mom every Friday and Saturday. Ellen only gets crushes on girls, never boys, and she knows she can always rely on her best-and-only friend, Laurel, to help navigate social situations at their private Georgia middle school. Laurel has always made Ellen feel like being autistic is no big deal. But lately, Laurel has started making more friends, and cancelling more weekend plans with Ellen than she keeps. A school trip to Barcelona seems like the perfect place for Ellen to get their friendship back on track.

Except it doesn't. Toss in a new nonbinary classmate whose identity has Ellen questioning her very binary way of seeing the world, homesickness, a scavenger hunt-style team project that takes the students through Barcelona to learn about Spanish culture and this trip is anything but what Ellen planned.

Making new friends and letting go of old ones is never easy, but Ellen might just find a comfortable new place for herself if she can learn to embrace the fact that life doesn't always stick to a planned itinerary.