Oscar faces a personal dilemma when he dates a young nanny, Allyson, who works for his neighbor, Charlotte. Also, Emily forces Felix to participate in an activity she's interested in, for a change.

Oscar attempts to impress Charlotte by purchasing a table for a fundraiser to benefit The New York Philharmonic. At the event, Felix reminds Oscar about the importance of being honest and Teddy introduces his wife, Diane, to Dani for the first time.

Oscar and Charlotte hit a speed bump when they hesitate to take their relationship to the next level. Also, Felix attempts to overcome his fear of dogs with Teddy's help when Emily regains custody of Biscuit.

Felix attempts to reverse Emily's birthday curse and plans a nice dinner to celebrate with friends. Also, Oscar and Charlotte face another obstacle in their relationship when Oscar meets Charlotte's son, Evan (Caleb Brown).

After Murph persuades Oscar to try online dating, Oscar finds himself on a blind date with Felix’s ex-wife, Ashley.

Oscar is forced to choose between his romantic plans with Charlotte and helping to save Felix’s relationship as Emily decides to extend her stay in London and Felix starts to fall apart.

Oscar sets out to prove to Charlotte how he's capable of being responsible when he volunteers to take her son Evan (Caleb Brown) trick-or-treating on Halloween, while Felix celebrates the holiday by leading the kids in their building on a haunted history tour.

Oscar arranges for Felix to replace him on any cultural outing that Charlotte has planned; and Emily recruits Dani, Teddy and Murph for help making 100 necklaces for an event.

Felix takes the first step in moving on from Emily by picking up a bartender named Natasha (Busy Philipps) and bringing her home for the night. It later backfires when Felix doesn't know how to have a one-night stand; Natasha starts to get attached and won't leave. Meanwhile, Oscar takes his relationship with Charlotte to the next level by asking her to leave her toothbrush at his apartment, after which they get into a conversation about their relationship and say "I love you" to each other.

Murph is hosting a new TV sports segment wherein Oscar is pitted against a penguin to pick the winners of hockey games. Oscar soon becomes the butt of jokes when the penguin's random picks (made by walking under one team logo or another) turn out to be more reliable than his. Elsewhere, Emily asks Felix to shoot photos of her for a jewelry website, but Felix misinterprets her verbal cues and thinks she wants to get back together with him.

After a heated argument, Oscar and Felix decide it might be best to change their living arrangements and find new roommates.