Riverdale Season 3 Episode 16 : Chapter Fifty-One: BIG FUN
As rehearsals for this year's musical "Heathers: The Musical" get underway, Cheryl, as queen bee Heather Chandler, channels her own HBIC to deal with a recent fallout. Meanwhile, Betty grows increasingly annoyed by Evelyn's involvement with the musical - as well as the lives of her friends. Elsewhere, Veronica learns some devastating news about her family, and Archie and Josie make a decision about their future. Lastly, Jughead makes a surprising move against Gladys.