Riverdale season 4 will open with a tribute to Luke Perry. The actor, who succumb to cardiac arrest after suffering a stroke in early March 2019, played Archie's dad Fred Andrews in the teen drama series and this episode will serve as the cast and crew's final tribute. 

Executive Producer Roberto Aguirre-Sacasa confirmed to TV Line that Riverdale season 4 episode 1 would be a standalone episode. The scribe said that it would have a different format and a different feel to emphasize the significance of this special feature. 

Featured in Riverdale season 4 episode 1 is Perry's former co-star and love interest in 90210 Shannen Doherty, whose casting was announced in July. Though Aguirre-Sacasa did not reveal what role she'll play, he hinted that her presence would nicely tie Perry, the actor, and Fred, the character, and it will be "super emotional." 

Doherty will also have a few scenes with the younger cast who were more than thrilled to work with a former teen idol in the 1990s. Riverdale star KJ Apa (as Archie Andrews) told the press that having Doherty as a guest in the tribute episode felt authentic and real that it didn't feel like work at all. 

Aguirre-Sacasa also said that they had tried for some time to get Doherty on the show even when Perry was still alive. It was one of the actor's wishes to have his old friend work with him again.

"The role would not nearly have the resonance it does if not for Shannen," Aguirre-Sacasa said. "She's just great in it because I think it's very real for her."

In response, Doherty posted on Instagram that she witnessed first-hand how much the cast of Riverdale loves Perry, who was also their mentor and caretaker. Doherty said that the special tribute episode was done with extreme care in memory of this actor with the kindest soul.

In May, Aguirre-Sacasa told Vanity Fair that they changed some of their original plans for Riverdale season 4 following Perry's death. Specifically, the overall tone of Archie's storyline has been rewritten to reflect this big loss.

Meanwhile, fans of the series can also expect Molly Ringwald, who plays Archie's mom, to pop in some episodes of Riverdale season 4, including the premiere episode. The series returns this Oct. 9 on The CW at 8:00 p.m.