[UPDATE] ‘Riverdale’ Season 1 episode 4 promo, spoilers: ‘The Last Picture Show’ [VIDEO]

Betty and Archie's friendship is on the line as Betty discovers something shocking about Miss Grundy's past in "Riverdale" Season 1, episode 4. Meanwhile, watch episode 3 of "Riverdale" online via live stream, here.

Warning: This article contains spoilers from "Riverdale" episodes. Read to know more.

"Riverdale" Season 1, episode 4 promo trailer

Note: The promo will be uploaded as soon as the network makes it available.

Update: Watch "Riverdale" Season 1, episode 4 promo, below.

"Riverdale" Season 1, episode 4 official synopsis

"When Jughead (Cole Sprouse) learns that an anonymous buyer has plans to tear down the local drive-in, he fights desperately to keep it open. Betty (Lili Reinhart) finds her friendship with Archie on the line after stumbling upon some startling information she's uncovered about Miss Grundy's (guest star Sarah Habel) past. Elsewhere, Veronica (Camila Mendes) confronts her mother Hermoine (Marisol Nichols) about a suspicious meeting she witnessed between her mother and a shady Southside Serpent. Finally, after uncovering Betty's diary, Alice (Madchen Amick) finds the perfect opportunity to destroy Archie's golden boy image. Madelaine Petsch and Luke Perry also star. Mark Piznarski directed the episode written by Michael Grassi," reads the official synopsis.

Meanwhile, Lili Reinhart, who plays Betty, spoke with TVLine and revealed that Betty let loose in episode 3.

In episode 3, Betty can't take the frustration building up in her life. She also talked about her character getting close to Cheryl.

"The dynamic changes once Betty uncovers more information about Polly and Jason's relationship in Season 1. It kind of brings them closer together once Betty... brings Cheryl into it," Reinhart said.

Stay tuned for more "Riverdale" Season 1 spoilers, news and updates.

"Riverdale" Season 1, episode 4 airs Thursday, Feb. 16 on The CW.

This article will be updated.

Credit: YouTube/Television Promos