Leslie's ex-husband Julius visits to finalize their divorce and in the process unearths some of Leslie's insecurities. The gang covers for her and Danny makes solid assurances that even though he and Julius were good friends, Leslie's his sister. At the apartment, Justin beams as he witnesses Leslie thank her brother for the support, only to see, moments after Leslie leaves, Julius emerge from Danny's room. It's all a lie - Danny is maintaining his friendship with Julius! Justin explodes over the betrayal... until the impossibly cool Julius wins him over with an impromptu acoustic sing-along.
Back at the bar, Danny lets the rest of the gang in on the secret and makes them promise to lie if the subject of Julius comes up with Leslie. This causes Justin - a self-described horrible liar - serious stress and when Leslie arrives he immediately jeopardizes the situation and makes her suspicious. Danny works hard to keep her off the scent, but Justin comes clean anyway and confesses to seeing Julius. His cover blown, Danny watches Leslie storm out of the bar in anger.
Danny and Justin head to Leslie's apartment to issue an apology. She greets them in a robe and appears distracted, which only makes sense when Julius enters from her bedroom - wearing nothing but a towel! Danny takes Leslie's move to sleep with her ex as reason enough to hang out with Julius in the open, until Justin points out Leslie's coping mechanism (heavy drinking) indicates maybe she regrets her decision. With Justin's encouragement, Danny confronts Julius with Leslie present and expresses his disappointment at Julius for taking advantage of his sister. Julius apologizes, but Danny takes it one step further and ends their friendship. Leslie and Danny hug, their differences resolved... and Justin's pride for his friend elicits an awkward but sweet group hug.