In "Welcome to the Black Dog House," summer has officially arrived on the island. Katie arrives on the Vineyard at a crossroads, in both her career and her relationship, while Emily is determined to find her very own "JFK Jr." Jackie has returned to the island to be closer to her mom, but once she meets Luis she quickly realized this summer will be filled with interesting possibilities. Ben confides in Cat about the real reason he's come home, but will she keep his secret? Meanwhile, the tension between Jon and Luis finally erupts at the welcome bonfire when they come to blows over Katie.