Seaside takes place in a small coastal town on the Bay of Somme. The year-round inhabitants find ways to make their lives work; Paul, a lifeguard in the summer, works at the grocery all winter. His mother, Rose (Ogier) likes to play the slots just about anytime; his girlfriend Marie works in the local factory - the town's biggest business - but watching the summertime vacationers each year just makes her increasingly curious about what else might be out there. From these and several other stories, aided by close, revealing observations, we see a community perched between transition and stasis.