When Sarah Wilson is named the new commander of a difficult military unit in Chioggia, Italy, she uproots her wife Maggie and teenage son Fraser from their lives in New York City to start a new chapter in this unfamiliar seaside town. While Sarah contends with her new position and Maggie resumes her work at the army's clinic, Fraser longs for Mark, a friend he left behind in New York, and seems uninterested in connecting with the other teenagers on base - until he meets Caitlin.
The arrival of Caitlin's period accelerates her secret desire to experiment with her gender expression - and to flirt with girls, test boundaries with her boyfriend Sam, and spar with her father Richard. As she and her brother Danny continue to clash with their mother Jenny, Caitlin's relationships with her both her dad and Danny's best friend Craig deepen. Later, Fraser discovers Caitlin's secret, which forever changes the nature of their relationship.
A fracture begins to form within the friend group following Caitlin and Sam's breakup. While Sam turns to the open arms of Britney, Caitlin is judged for spending more time with Fraser. Later, Maggie attends the Chioggia Festival with the neighborhood women and finds an unexpected companion in Jenny. Meanwhile, the progress Colonel Wilson has made in her new role is derailed when she decides to deploy her troops early - and her complex relationship with Fraser is rattled when his crush becomes her only ally.
With his deployment timeline fast-tracked, Craig spontaneously proposes to his Italian girlfriend, Valentina. Determined to ship him off with a celebration he'll never forget, his friends pool their resources for a Hawaiian-themed wedding that leads to an evening of debauchery.
As the power struggle between Sarah and Richard escalates, the relationship between their wives continues to grow, and Sarah fuels the fire by spending time with Caitlin on the base's virtual shooting range. Later, Caitlin asks Fraser for help making a bold statement; Danny questions Jenny about his biological father as he dives deeper into Islam; and Fraser forms his own connection with Jonathan.
Sarah is thrilled to learn about her son's burgeoning friendship with Jonathan and, grateful for a strong male influence in Fraser's life, encourages them to spend more time together - even if Maggie doesn't understand. Richard uses a father-daughter hunting trip to get inside Caitlin's head. Later, Sarah receives a phone call that will forever alter life on base.
The friend group fractures even further over their hatred for Colonel Wilson, whom they blame for a tragedy that's rocked the base. As Caitlin momentarily pauses her self-discovery journey and Danny fully commits to his, Richard's insubordination reaches a breaking point, forcing Wilson to make a difficult decision.
In honor of her last day in Italy, Caitlin and Fraser sneak off to catch a concert in Bologna. Along the way, Fraser finally feels comfortable admitting a shocking secret about Mark and finds a new friend in Luca before he and Caitlin spend their final moments together in the most beautiful place on earth.