The emotional effects of an extramarital relationship are explored when a married schoolteacher begins an affair with a waitress on Long Island. In the opener, Noah Solloway and his family visit Long Island where he connects with a local waitress.

As the Butler estate readies for the annual summer party, Noah can't escape the allure of the mysterious Alison. She, meanwhile, bends under the emotional debt owed to her mother-in-law. But as aspects of their separate lives start to weave together, the two are forced to consider an inevitability.

With his novel gaining traction, Noah turns to Alison to help him research the local culture - but their innocent tour of Montauk proves more dangerous than expected. Meanwhile, Cole takes a stand on behalf of his community, and Helen deals with business back in Brooklyn.

In order to spend time together apart from their families, Noah and Alison take a day trip to remote Block Island. But as the two grow closer, they quickly learn that intimacy can be a double-edged sword.

As passions flare behind closed doors, Alison and Noah are forced to confront new obstacles at home. Alison gets a surprise visit from her estranged mother, Athena, while Noah struggles with the behavior of his daughter, Whitney.

After Noah spends a night out with his best friend Max, he discovers there's more to Alison than he's been led to believe. At home, his wife Helen hopes to make the most of the family's time in Montauk. Meanwhile, Alison and her husband Cole work to keep the Lockharts from danger.

With summer coming to an end, the Solloways are returning to Brooklyn - a welcome relief for Noah following recent revelations. Meanwhile, Cole is forced to confront Alison when the Lockhart side business hits too close to home. And Helen and Noah grapple with the results of an unexpected emergency.

Distracted by her burgeoning small business, Helen tasks Noah with representing the family at a literary award ceremony for her father, Bruce. A chance encounter with Alison and her grandmother leads to an uncomfortable truth.

A revelation about their daughter Whitney makes Noah and Helen realize their troubled marriage is directly affecting their children. Bending under remorse, Alison spirals towards a reckoning.

The disappearance of Whitney spurs Helen to scrutinize Noah and his relationship with Alison and her family. Cole searches for answers at Lockhart Ranch. Meanwhile, Detective Jeffries makes significant progress on his case.