When the popular teen drama The O.C. was airing in the early 2000s, fans of the show were shocked when leading lady Marissa Cooper, played by Mischa Barton, was gravely injured in a car accident and died in the arms of her love interest, Ryan. The wealthy California native was one of the four core characters in the show, and she went through several tense and dramatic storylines before her untimely death in Season 3.

But while Marissa wasn’t the most popular character and tended to be selfish, narcissistic and self-destructive, her death still came as a surprise to fans. Here’s how the character died on The O.C., and why Mischa Barton decided to leave the series.