Despite Lena and Martin getting along as co-parents, they must determine the best way to orchestrate Milo's upcoming birthday festivities based on their new system of boundaries. Meanwhile, Oliver is pleasantly surprised when Jenna shares a birthday invite with an unforeseen guest. Elsewhere, Maya takes matters into her own hands and reveals a surprise guest of her own.

After Lena and Martin sleep together, Lena searches for signs that they are or aren't meant to be a couple; Arthur and Camille trail Lisa Apple, hoping to determine if she is pregnant with Martin's baby.

Martin finds every way he can to avoid asking Lisa Apple if she is pregnant; Lena worries Mason is changing himself to please his new girlfriend; Maya tells Frank a made-up story about a friend who is dating someone new.

Lena decides to call Martin's bluff on selling the house but is surprised when he begins getting the house ready for sale; Lena tries to cheer up Mae by inviting her friend from camp to visit; the friend seemingly brings supernatural events with her.