Serious Mothing is the second episode of the first season of Big Little Lies
Jane deflects Ziggy's questions about moving to Monterey; Celeste suggests she and Perry see a counselor; Nathan and Ed hope to smooth the tension between their wives and themselves. 
The episode opens with Madeline and Chloe talking about how the ocean is the great unknown. Jane and Ziggy are getting ready for school. Ziggy doesn't want to go but Jane forces him to. Celeste and Perry are taking the boys to school. Celeste suggests that they go see another counselor, to which Perry agrees. Once they get to the school, Perry is upset that he can't get off and meet the kid's teacher. Celeste explains that that happened on orientation day.
Madeline and Celeste go to a yoga class. Madeline gets upset when she notices that Bonnie and Nathan go to the same class. Madeline decides that she's never going to take that class again. On the first day of school, the kids have to work on a family tree project. Amabella hands out invitations for a party and fails to invite Ziggy. Celeste and Perry have a fight at home about the first day of school. He believes that Celeste didn't want him at orientation. He slaps her, she slaps him, and he throws her against the closet. He begs her to forgive him and blames his abuse on his constant traveling. They proceed to have rough sex against the wall.
Madeline and Jane pick up Ziggy and Chloe Ziggy didn't invited to Amabella's party and Madeline gets upset. She goes home and complains to Ed. Ed says that Renata has a right to invite who she wants but Madeline doesn't agree that inviting the whole class except one is alright. Madeline storms off and Ed follows. They have a big fight about Nathan. Ed wants to know if Nathan was the one for Madeline. He accuses her of still being in love with Nathan. Ed says that Madeline is his one and that he is sick of her being dissatisfied with her life. He tells her that he won't be anyone's runnerup.
Celeste's twins, Josh and Max, are the ones who get to take the class hippo home first. They ask if they can invite Ziggy over but Celeste says that she has to ask their dad first. Madeline calls the two of them go to trivia night. Celeste reveals that Perry and her argue before they have sex. That sometimes she likes it and sometimes she doesn't. Madeline says that's twisted. Renata interrupts their conversation to complain about the closing of the vet hospital. Madeline confronts her about failing to invite Ziggy. Madeline says that if she doesn't invite him, Chloe and her friends wont be going. Renata tells her to don't mess with her daughters birthday. Madeline declares that the war is on.
Madeline and Abigail have an argument about birth control. Abby reveals that Bonnie took her to Planned Parenthood to get it. Madeline confronts Bonnie at school and yells at her for taking her. That if her daughter ever came to her she'd ask Bonnie first before taking her. Ed and Nathan meet up to discuss what's going on between their wives. Ed believes that Madeline is being nice to Bonnie and that Madeline's mad at Nathan because he was never there for Abby. Ed wants him to be mindful of other people's feelings. Nathan starts to tease him about being a "modern man" and how they are so not alike. Ed reveals that he was bullied in elementary school and that one day if someone ever did something to him again he'd use that to redeem himself.
The Mayor has denied funding for the community play. Madeline believes that Renata is behind this. Madeline learns that Disney on Ice is at the same time as Amabella's birthday. So she invites everyone to go to that instead of the party. Jane gets called into the school and learns that Ziggy and Amabella kissed. Chloe had orchestrated it so that the two could make up. Jane breaksdown crying because she doesn't know what to do.
Celeste and Perry skype. Perry asks Celeste to get naked for him. She says no but he convinces her to anyways. Ziggy reveals that he saw Jane have a breakdown. He also says that the kids are calling him a monster. She insists that he isn't a monster. Madeline asks Abigail if they can talk about her having sex before she has it. She agrees. Madeline and Ed talk about his conversation with Nathan. He says that he's got her back and Nathan's got Bonnies. She reveals that he is her only one.