Lucy struggles to get patient Valerie in for surgery when an infection threatens her heart transplant. Carter and Chen disagree over the treatment of an elderly woman and her care-giving daughter. Mark tries to help an abusive gay couple. Carol has trouble adjusting after her return from maternity leave. Dr. Dave goes out of his way to shut an illegal pharmacy down. Luka treats some circus performers. The ER suffers from a water shortage. Benton asks Cleo out.