'Big Little Lies' episode 5 spoilers: Ziggy crosses the line; Madeline betrays Ed

Promotional photo for "Big Little Lies" | Twitter/NicoleKidman

Ziggy (Iain Armitage) will be crossing the line with something that he'll do to Amabella (Ivy George). Meanwhile, Madeline (Reese Witherspoon) will be doing something to betray her husband, Ed (Adam Scott).

On the next episode of "Big Little Lies," titled "Once Bitten," Ziggy will be biting Amabella, which might bring the school's principal to kick him out.

"Madeline receives encouraging news about the play from her director, Joseph Bachman (Santiago Cabrera), but is left concerned by his newly icy demeanor. Principal Nippal (P.J. Byrne) and Ms. Barnes (Virginia Kull) share their conclusions about Ziggy and Amabella with Jane (Shailene Woodley). Celeste (Nicole Kidman) has a solo session with Dr. Reisman (Robin Weigert), who tries to get to the bottom of Celeste's troubling relationship with Perry (Alexander Skarsgard)," the episode's description found on the HBO website reads.

As seen from the episode 5 promo, Renata (Laura Dern) shrieks in anger as she finds out that her daughter has been bitten on her back.

Later on, it was also shown that Madeline is having a sexual moment with someone inside a car. Ed senses that Madeline is hiding something from him, and it catches her off guard.

It is possible that Madeline was with her ex-husband Nathan (James Tupper) in the car, which led to them doing the deed. How will Ed react when he finds out about what Madeline did and who she was with?

In an interview with The Hollywood Reporter, Scott, who portrays Ed, shared that there is a lot more to his character than being the invisible guy. Scott said that his character will begin to stand up more over the course of "Big Little Lies" and that Ed is not crossed off on the list of suspects to the murder that will happen in Monterey.

"Big Little Lies" airs every Sunday night at 9 p.m. EDT on HBO.