Roberto Aguirre-Sacasa has shared new details about Riverdale's tribute to the late Luke Perry.

The 52-year-old - who played Fred Andrews on the CW series - passed away in March, five days after he suffered a stroke. The first episode of season four will be dedicated to Perry, as well as his character Fred Andrews, and - according to Aguirre-Sacasa - is unlike anything they have done before. Explaining that it is “very much a standalone episode,” the executive producer told TVLine that they got rid of the 'previously on' recap that each episode normally has. “After we finished the episode, everyone said, ‘You know what? You don’t really need that,'" he continued. Aguirre-Sacasa added that the producers had decided they wanted "a little bit of extra time", which led them to decide to remove the 'previously on'. "We wanted to let the episode breathe a little," he said. Shannen Doherty, Perry's former 90210, is going to guest star in the first episode of Riverdale's season four. And while her character's connection to Fred hasn't been revealed just yet, Aguirre-Sacasa did share a few details about her "wonderful" role in the episode. “The role would not nearly have the resonance it does if not for Shannen. She’s just great in it, because I think it’s very real for her," he said. He also confirmed that her charter shares a scene with Riverdale's teenage characters, which serves as “a powerful moment of catharsis.”

• The new season will start on the CW in North America on Wednesday, October 9. Episodes will arrive on Netflix in Ireland the following day, October 10 - most likely around 8am.