Milo complains that Grandparents Day is coming up at school and doesn't feel Henry is interesting enough to participate. Lena and the kids urge Martin to reconnect with his long-estranged father, Brock, to rebuild their relationship. Meanwhile, Lisa continues to struggle financially and considers moving back home with her parents. Elsewhere, after listening to a true crime podcast, Maya worries that Frank has a dark past he has been hiding.
In an effort to connect with their kids and bring the family closer together, Lena and Martin plan a fun outing, only to be interrupted by a blackout. Elsewhere, Lena urges an overdue Maya to get induced but must succumb and honor her birthing plan. Meanwhile, Martin continues to try and figure out where his relationship with Lisa stands.
Lena and Martin announce to the kids that Lisa Apple's baby, Annie, is their half-sister, and Martin is surprised when they aren't interested in meeting her. Lena feels the burden of being stuck in the middle between Martin and Lisa but still offers to help bring both families together. Meanwhile, Mason overhears Lena and Martin's conversation about Lisa's financial difficulties and decides to start a fundraising campaign to help. Elsewhere, Lena feels a bit of empty nest syndrome.
Martin grows suspicious of Lena's strange behavior when she begins sneaking out of the house to secretly help Lisa Apple with her baby. Lena tries to avoid Martin but feels she needs to tell him the truth about her arrangement with Lisa. Meanwhile, Martin takes Mae on a driving lesson, which turns into a hot pursuit.
Lisa's unexpected pregnancy causes more complications than what Lena and Martin anticipated. Without Martin's knowledge, Lena decides to help Lisa despite her insistence about not wanting them involved in the baby's life. Meanwhile, Mae and Mason try to force Lena to admit that she and Martin are back together. After Maya's false labor scare, she returns from the hospital and is put on bedrest by Frank who insists on taking care of her.
Lena confirms that she has feelings for Martin but is confused when his response is not what she expects. To escape the situation, Lena joins Camille and Maya on a road trip for a girl's weekend before Maya's baby arrives. Meanwhile, Martin, still considering how to respond to Lena, joins Arthur, Frank and Henry in chasing after the women.