A power outage strikes on an unusually hot day, bringing nursing home patients suffering from hyperthermia to the ER. Abby and Pratt disagree about diagnostic tests for a fussy baby. Morris and Pratt get their board results, and the ER staff celebrates at Ike's. Moretti and Abby's interactions intensify, and Abby finds herself at a dark and frightening crossroads.

The staff must deal with changes in the ER when Anspaugh makes an unpopular decision. Abby has old demons to fight, distancing her from friends and family. A patient's racist son makes a deadly mistake. Two doctors secretly become involved. Gates has some adjusting to do when Sarah returns to Chicago. Luka gets bad news from Croatia.