They're still playing with fire.

Season 4 continues to provide exciting moments. Tommy is unable to recall the events of the beach-house fire for which he is under investigation for. Meanwhile on the home front, he disapproves of his daughter's rebellious behavior. Richard wants Franco to marry Natalie so he can have more freedom. Lou and his new girlfriend decide to make love in the "holiest" of places. Newlywed Garrity is uncomfortable with Maggie's collection of porn movies.
Tommy meets with Sheila in hopes of finding out what really happened on the night of the fire. Lou has his sights set on a new recruit who can really help the squad's basketball team. Teddy is released from prison. Tommy's daughter Colleen is believed to have run away from home.
Tommy confronts Colleen and her new boyfriend. Probie must make a crucial decision regarding his terminally-ill mother so he asks Tommy for advice. Natalie is upset at Franco for not considering marriage. The Chief is forced to leave the firehouse because of health issues and decides to take a desk job. Tommy resists the advances of the volunteer firefighter who previously pulled him out of a fire.