Somebody's Dead is the pilot episode of the first season of Big Little Lies
A suspicious death at a coastal elementary school fundraiser draws attention; An incident with the children at school causes battles lines to be drawn. 
The episode opens at the school fundraiser. Someone has been murdered. The victim suffered a broken pelvis and a fracture at the base of the skull. There are no suspects as of yet. The guests at the fundraiser a brought in for questioning. The episode is told from their testimonies.
Everything can be traced back to the incident on orientation day. It all began with Madeline Martha Mackenzie. Madeline catches her daughter Abigail Mackenzie driving with a teenage driver who'd been texting. She scolds her daughter and threatens to tell the driver's mother. As Madeline walks away, she falls. Jane Chapman sees this and gets out of her car to see if she's okay. Madeline seems to have rolled her ankle so Jane offers her and her youngest daughter Chloe Mackenzie a ride to school. Madeline introduces Jane to Renata Klein and Celeste Wright along with her ex-husband Nathan and his girlfriend, Bonnie Carlson. After they drop the kids off, Celeste, Madeline, and Jane head to get some coffee. Celeste and Madeline grill Jane about her past.
It cuts to Jane running along the beach and then to Bonnie's yoga class. Bonnie and Nathan argue about who is going to pick up the kids. Bonnie says that she will but Nathan is worried that Madeline will be hostile with her. Bonnie wants to stop the play from happening and this causes a rift between them. Back at school one of the teachers makes an announcement that someone has hurt Amabella Klein, Renata's daughter. She encourages the children to step forward and confess but no one does. Amabella points at Jane's son, Ziggy. Ziggy says that he didn't do anything wrong. Madeline tries to step into the middle and ends up angering Renata, who storms off.
Madeline and her family are having dinner and discussing the incident. Abigail makes Madeline mad by saying that Ziggy was in the wrong. Madeline storms off and her husband Ed follows. Madeline is upset that Abby likes Bonnie more than her. That her children are leaving her and that she has nothing once they're gone. She complains that Nathan got all the good side effects from their divorce and she got nothing. Ed is offended but says that they'll argue about that another time.
Renata sits on her balcony and complains to her husband, Gordon, that she isn't liked. She blames it on her job and how mom's shouldn't work once they have kids. Her husband says she's being difficult so she storms off. Jane argues with her Mom on the phone and hangs up as she gets ready for bed. She has flashbacks from what looks like her prom night. Jane goes to check on Ziggy who asks if he's in trouble. She says no but asks if he did touch that little girl. Again he says no.
Madeline and Abigail talk about college. Abby says that she doesn't want to go to college. Madeline disagrees and says that she has to. Abby argues that you don't need college to succeed. Madeline says that Bonnie doesn't know everything and that Abby needs to be educated so that she can be strong and independent.
Celeste and Perry talk about the incident. He doesn't want his kids to play with Ziggy . He feels that Ziggy will be a bad influence. Celeste disagrees and says that Ziggy is a sweet kid and may be innocent. She says that he's being ridiculous and walks away. Perry chases after her and grabs her by the neck. He threatens her and tells her that she needs to look out for the children when he can't. She pushes him off her and walks away.
The episode ends with a montage of the police officers investigating the murder.