The fourth season premiere finds the gang adjusting to life without Marissa Cooper. Summer is attending Brown University in Rhode Island, where she has reinvented herself as a left-leaning, tree-hugging activist under the sway of environmentalist Che (guest star Chris Pratt). Ryan has moved out of the Cohen house and is dealing with Marissa's death in the only way he knows how. When he misses a special dinner at the Cohens, Seth finds him on the wrong side of the tracks and calls Summer for help. Meanwhile, Julie Cooper will do anything — even yard work—to avoid dealing with Marissa's death; Kaitlin earns a new pair of boots from Dr. Roberts in true Cooper fashion; and Taylor hides out in the diner trying to convince her friends she's still in Paris in "The Avengers" episode of "The O.C."