In a town full of secrets, a group of teenagers are stalked by a mysterious killer a year after a fatal accident on their graduation night.
Lennon Grant returns home after her first year at college and discovers that someone knows the terrible secret she and her OG crew of friends swore to keep last summer.
The estranged friends reunite to try and figure who might have revealed their secret or who else knows what they did – which leads to murder.
Unable to go to the authorities without revealing their secret, the crew needs to solve the mystery on their own. More bodies turn up, as they realize they're being haunted and hunted.
Lennon uncovers secrets about her twin and begins to fear the worst about the true identity of the person murdering her friends. The local community is shocked by more murders.
The police question everyone in town with any connection to the victims. The crew think they know who is after them and hunt for evidence implicating the town eccentric.
More devastating truths are unearthed by Lennon as the crew frantically search for one of their own who has gone missing.
The town races to find the killer before another victim is claimed. Calm seems to be restored as the killing stops until the police make a gruesome discovery.
Lennon and her surviving friends confront painful truths from the past as the shocking truth of the killer's identity is finally revealed – with deadly consequences.
Complete episode guide for I Know What You Did Last Summer with detailed information about every season and episode including air dates, summaries, ratings, and streaming availability in France.
This episode guide is organized by seasons, making it easy to track your viewing progress or find specific episodes. Use the episode information to plan your binge-watching sessions or catch up on missed episodes.