After her break-up, Shay decides she wants to have a baby by herself. Gabby, Herrmann and Otis track down the owner of the box they found in the safe. At the scene of an accident, Peter Mills bravely talks a man out of suicide. Later, at the annual Academy Dinner, Gabby and Peter come out as a couple, Gabby overhears Benny Severide reveal a big secret about the death of Peter's father, and Andy Darden's widow surprises Casey.