Mark must overcome numerous obstacles, mostly weather-related, in order to get to the church to marry Elizabeth, who is stuck with both of her bickering, divorced parents. Abby has a major cold, but cannot leave the hospital, due to most of the nurses being at the wedding. Many patients come in to the ER from an accident involving a prison van; Luka and Carter clash over the treatment of an injured cop and a prisoner with a dislocated shoulder. While waiting for a flight to Vegas, Weaver (who wasn't invited to the wedding), strikes up a conversation with a friendly man. Chen misses her son. Cleo doesn't want to go to the wedding, because the bride is Peter's ex-girlfriend.