I Know What You Did Last Summer Spoilers: Killer, Kills, Cameos & Credits Surprise Revealed!

The new I Know What You Did Last Summer takes some pretty massive swings, sure to both divide and excite fans of the 1997 original and its 1998 follow-up, I Still Know What You Did Last Summer.

That's right, even the less-well-received sequel, which co-starred Brandy and Mekhi Phifer, is referenced in the new film, directed by Jennifer Kaytin Robinson and written by Robinson and Sam Lansky.

This time around, the story revolves around a new group of young adults, who accidentally cause another car to drive off a cliff, killing the driver, after a night of drinking on the 4th of July. One year later, a hooked fisherman starts killing them one by one, as survivors who faced a very similar situation nearly 30 years ago -- Jennifer Love Hewitt and Freddie Prinze Jr.'s Julie James and Ray Bronson, respectively -- are pulled back into the plot.

Along the way, pretty young people are strangled, gutted, have their throats slashed and are speared to death, before another actor from the original movie makes a pretty surprising cameo.

Despite her insistence in interviews before the film's release that she wouldn't make an appearance, Sarah Michelle Gellar -- whose character Helen Shivers was killed after an amazing chase sequence back in '97 -- pops up about 2/3rds into the film.

Her cameo comes thanks to a dream sequence for Madelyn Cline's Danica -- a fellow "Croaker Queen" who fits the mold of Helen's character. Holding onto the fisherman's hook and wearing her beauty queen crown, Helen stands over the body of Danica's ex on the beauty pageant stage, as Danica says she recognizes her from photos all over town. After a warning that Danica and her friends are all going to die for the cover-up the previous year, Helen starts to transform into a zombie, before Danica wakes up.

From there, the movie revs into the final act.

Following the brutal murders of characters played by Joshua Orpin, Gabbriette, Tyriq Withers, Jonah Hauer-King, Austin Nichols and Billy Campbell, Cline, Chase Sui Wonders' Ava and Sarah Pidgeon's Stevie take off on a boat, hoping to escape a similar fate. The only problem: Stevie is the fisherman ... or, at least, one of them.

Turns out the guy they killed the previous year was actually one of her friends, a man named Sam, something she didn't realize until his body later eventually washed ashore. He was actually on his way to see her when his car ran off the road, concerned Stevie -- fresh out of rehab -- was about to relapse, a fact which only devastated her further when she learned the truth. While she considered suicide, she opted for homicide instead -- and started picking off everyone in her former friend group.

Danica is stabbed and tossed overboard, before Ray arrives and shoots Stevie, sending her into the blue too.

Case closed, right? Nope!

Ava calls Julie once back at Ray's bar, wondering how Stevie could have acted alone ... before it clicks for Hewitt's character that she didn't. Stevie had help, in the form of Julie's own ex-husband, Ray. As she rushes to help Ava, Ava pieces it together too and she has her own fight with Ray.

As for his motive? One, he became a paternal figure to Stevie after the girl's father left town and, two, he was ticked at what became of his home, Southport. He felt the town did everything it could to erase what happened to him and his friends back in '97, almost rewriting history ... and planned to frame Julie for all the new murders. So while Julie turned her trauma from two killing sprees into a successful teaching career, Ray became the killer he used to run from.

As Julie shows up for a showdown and lets out one final "What are you waiting for?!", the two come to blows, before Ava offs him with his own harpoon.

It's a bold choice to make one of the original survivors the killer ... and one that may not sit well with a lot of fans who have reverence for the first two movies. It's something fans of another slasher franchise, Scream, have theorized would happen to Final Girl Sidney Prescott, played by Neve Campbell for years. Now that IKWYDLS beat them to it, it's probably safe to say that will never happen (and probably never should have in the first place).

In the final moments of the movie, viewers see that Danica managed to wash ashore, alive, before learning that Stevie is still alive too. "Should we kill her?" asks Danica, before Ava replies, "Probably."

We don't actually see Stevie, but someone is clearly still out there, coming for Julie and another familiar face.

In a mid-credits scene, the audience sees Brandy's Karla watching news coverage of the latest murder spree, as she comments on how someone's always trying to kill her former roommate. Just then, Julie shows up at the door -- after being sent a note reading, "IT'S NOT OVER," along with a photo of the two of them from the '90s, with Karla's face X'd out.

"Who are we f--king up this time?" asks Karla, before Julie replies, "I was really hoping you'd say that," as the two set up a sequel we'd really love to see.

I Know What You Did Last Summer is in theaters now.