Riverdale 3×20 “Prom Night” Season 3 Episode 20 Sneak Peek – CHAOS ON PROM NIGHT — Betty (Lili Reinhart) takes matters into her own hands after learning some unsettling news about her father. Mary (guest star Molly Ringwald) grows concerned by Archie’s (KJ Apa) desire to take boxing to the next level. Elsewhere, Cheryl (Madelaine Petsch) runs into a roadblock during her campaign for prom queen, while Jughead (Cole Sprouse) and Betty’s plan to confront the Gargoyle King takes an unexpected turn. Camila Mendes, Marisol Nichols, Madchen Amick, Skeet Ulrich, Casey Cott and Vanessa Morgan also star. David Katzenberg directed the episode written by Britta Lundin & Devon Turner (#320). Original airdate 5/1/2019.