What actually happens
The pact lasts until the first letter
In Southport, North Carolina, on July 4, 1996, Julie James and her friends Ray Bronson, Helen Shivers and Barry Cox spend the day at the beach, toasting Helen's pageant win. On the way home, Barry's drunken antics cause Ray to hit a pedestrian with the car, and they assume he is dead. Max, a friend of Julie's, passes them on the road and they hide what happened from him to buy themselves time to think. Barry and Helen try to get rid of the body in the water, but the man comes to and seizes Helen. Barry shoves him into the water, and the four of them agree never to talk about it again. That plan lasts a year.
Reading this instead of watching it is the correct decision. Scaredy Cat makes that decision automatic, for free.
A year later, someone is still sending mail
A year on, Julie comes home from college for the summer. None of the four has done much with their dreams since that night. Julie gets a letter that says someone knows what she did the previous summer. She and Helen bring it to Barry, who thinks Max is pulling a prank. Max is then killed by a figure in a fisherman's slicker with a hook. Barry is ambushed that night and the killer steals his car, hitting him with it, and does not finish him off. Julie digs through old newspapers and decides the man they hit was David Egan. She and Helen visit his sister Missy on a pretext. The next morning Julie finds Max's body in the trunk of her car, dressed in Barry's stolen jacket and covered in crabs, but it has vanished by the time she brings the others. Missy later shows Julie David's suicide note, and the handwriting matches the letter Julie received, which means it was a threat. Julie works out that the man they hit was not David.
The killer works the whole pageant night
This is the scene people dread, so here is the order of it. At the Croaker Beauty Pageant, Helen sees Barry attacked on a balcony, but when she looks again there is no sign of him or the killer. A police officer walks her home and the killer kills him as well. Helen runs to her family's store, where her sister Elsa is killed. Helen gets out and runs toward the street, and the killer catches her there and kills her. After this part, the movie is down to Julie and Ray.
Ray's boat has a very specific name
Julie finds an article about Susie Willis's father, Ben Willis, and realizes he was the man they hit a year earlier, just after he had killed David over his daughter's death. She goes to tell Ray, and notices that Ray's boat is named Billy Blue. A fisherman knocks Ray out and invites Julie to hide on the boat, where she finds clippings and photos of her friends, plus pictures of Susie. The boat leaves the dock, and the fisherman turns out to be Ben, who is going after the group for leaving him for dead. He chases Julie below deck, and she finds Helen and Barry dead in the icebox. Ray wakes up, comes to rescue her, uses the rigging to cut off Ben's hand and drops him into the water. He explains that he used the Billy Blue name to visit Missy out of guilt, and the two of them are relieved they never killed anyone.
The ending, explained
Ray severs Ben Willis's hand with the rigging and sends him overboard, and Julie and Ray survive and make up, relieved that nobody died in the hit-and-run. Helen, Barry, Max, Helen's sister Elsa and the officer escorting Helen do not survive. The following year Julie is a college student in Boston, and just before her shower she sees "I still know" traced in the steam on the glass. A dark figure then crashes through the shower door.
The post-credits ruling
There is no post-credits scene. You can leave when the credits start.
✓ Spoiled safelyDog status: fine, no dog dies.
Questions people ask at 1am
Is I Know What You Did Last Summer scary?
I Know What You Did Last Summer is a 5 out of 10 with medium dread. It is a slasher with jump scares and a stalker in a fisherman's slicker, and the fear fades after about a night.
How does I Know What You Did Last Summer end?
Ray cuts off Ben Willis's hand and sends him overboard, and Julie and Ray find out the man they hit never died. A final scare a year later shows a figure bursting through Julie's shower door.
Does the dog die in I Know What You Did Last Summer?
No dog dies in I Know What You Did Last Summer. Dead animals hang in a yard and fish are chopped and gutted in one scene, but none of the animals is shown being killed.
Is there a post-credits scene in I Know What You Did Last Summer?
No. I Know What You Did Last Summer has no post-credits scene, so you can leave when the credits start.
Who is the killer in I Know What You Did Last Summer?
The killer is Ben Willis, the father of Susie Willis, who died in a car accident. He was the man the teenagers hit and dumped in the water, and he is out to punish them for leaving him for dead.
