Baby Lillian, a dear little three-year-old, is the unconscious medium through which Tom Downey. Captain of Engine Co. 24, falls in love with little Widow Marming, the baby's mother. The fire inspectors decide that "Old Billy,'" the veteran horse of No. 24, has outlived his usefulness to the service, and he is therefore sold at auction, much to the dislike and regret of the widow, Baby Lillian and Tom. The once proud fire horse now descends to the burden of a milk wagon. Six months later, while "Old Billy" is peacefully standing before a house on his master's milk route, a fire breaks out in the apartment house occupied by the little widow and her child. Tom and his company are quick to respond, and as the engines go down the street, they pass "Old Billy." This is too much for the hero of many fires, and forgetting his quiet occupation, he falls in line and dashes madly after the disappearing engines, the milk cans leaving a trail behind him. Tom meantime has saved his sweetheart and her child from the burning building and they recognize their old friend. Tom buys him from the irate milkman, who arrives at this moment. A wedding follows the fire, and "Old Billy" is among the happy ones present.