CHICAGO FIRE — “One Hundred” Episode 508 — Pictured: (l-r) Monica Raymund as Gabriela Dawson, Jesse Spencer as Matthew Casey — (Photo by: Matt Dinerstein/NBC)

Name of the Episode: “One Hundred”

Gabby is still reeling from her parents divorce announcement. She now questions the sanctity of marriage and what it means. Casey tends to Louie in the morning and sees a man in the alley leering, but steps away out of sight. At the firehouse, Herrmann is discouraged by Molly’s lack of earnings over the past months. The team is called to a home where an explosion was heard. Severide discovers the tenant was cooking drugs in the basement and the combination caused a fire and explosion. Severide was able to save the young man from any serious injuries, but Severide himself got a slight burn on his neck.

Back at the firehouse, Otis takes a look at Molly’s books trying to find a solution for their loses. The deed shows the original opening year was 1916; which means their 100-year anniversary is coming up. Otis hopes the centennial celebration will draw more patrons to the bar. Severide confides in Casey about not knowing where his life is going. Casey suggests a boys fishing trip to get their mind off everything. Gabby and Casey get some good news about Louie; they will be put on a fast track to make the adoption final. Even though Gabby and Casey are living together, the court will see Gabby as a single parent. More than anything, Casey wants to be viewed as mom and dad to Louie.

While waiting for their next call, Boden orders Severide to visit Med to get his neck injury fully taken care of. While at the firehouse, Casey sees the hooded man from the neighborhood standing outside. He goes outside to confront him, but the man gets in his car and speeds away. Casey then faces another problem; trying to adopt Louie as co-parents has a slim chance of happening. So, Casey encourages Gabby to move forward with the adoption alone. Meanwhile at the firehouse, Otis faces backlash from a reporter finding out the bar suffered a massacre in the prohibition era. Herrmann wants to cancel the party to save any of their finances. As luck would have it, a call comes in for a massive car and civilian accident.

The team works skillfully and quickly to get everyone to safety. After they finish the call, the truck head straight for Molly’s because of a crime tour bus came by. Molly’s is able to celebrate with the Chicago neighborhood and toast to many successful years to come. While Herrmann is toasting to the crowd, Casey becomes overwhelmed with the words and takes Gabby to the courthouse. They thought they could sneak away, but the firehouse family has to come along. Surrounded by their family, Casey and Gabby take their vows to become of one heart. Severide had been dragging his feet about getting his bone marrow tested because it takes a lot of time. Clarke sees a female patient who needs a transplant and has a similar ancestry background to Severide. Clarke knows it would be a slim chance to match, but he wants to help save a life because she may not have much time.

After the ceremony, Severide went to the hospital and makes the commitment to be tested. Casey and his new family are walking home feeling so joyous. Once they reach the front door, Casey once again sees the hooded man standing in the shadows. He confronts the man and asks what he wants. The man simply states that he is Louie’s father, and he wants custody.

Chicago Fire will return January 3, with a crossover of Chicago P.D. Severide is being accused of a hit and run that soon turns to vehicular manslaughter. Is he innocent? Or will he be convicted of murder? Find out in a few weeks when Chicago comes back in the new year!