Warning: This article contains spoilers for Chicago Fire Season 8 Episode 4, titled "Infection, Part I," that may spoil your enjoyment in discovering its plotlines. Read at your own risk.

Next week's episode is about to feature a big crossover event. Things will be more intense with the spread of a new infection and some deadly bacteria that the rest of the team needs to work out to save lives before it's too late.

"In the first part of a three-show crossover event, a rare but deadly bacteria takes its toll on numerous victims around the city, leaving Chicago's finest first responders to work together alongside the CDC to resolve the dangerous situation," Chicago Fire Season 8 Episode 4 official synopsis read. "Following a fire at a local university that ties into the outbreak, Severide (Taylor Kinney) has suspicions that something bigger is happening."

According to CarterMatt, this episode will establish everything that will happen in the crossover. This storyline will be featured in other shows as well, but there will be a few specific things that will carry the mark of Chicago Fire and its team.

The crossover event will feature a balancing act that will make it as strong as it is. It will make sure fans will keep watching the show's every episode, instead of just seeing some of the cases. Although there are questions if it will be an outstanding crossover, the series promises it is one of the most ambitious it has ever done.

Meanwhile, Brett (Kara Killmer) is finally backed in Chicago Fire. After breaking off her engagement with Kyle (Teddy Sears) and leaving Indiana, she returned to Firehouse 51. Killmer told TV Line her character felt mixed emotions when she made a comeback.

Now that Brett is backed, it only means she would be reunited with the firefighter captain, Casey (Jesse Spencer). The two's first interaction surely made fans giggled. Spencer himself said their reunion was a "good one."

Sure, they are good friends, but it looks like something romantic will brew between the two. Although it is yet to be revealed what will happen in the next episodes, Spencer teased that they are now playing with the idea. If it happens, he hinted it would be a long game, as it would never going to happen too quickly.

By the looks of it, fans have a lot to see this season from the reunion of Casey and Brett to the issues Firehouse 51 has to face. Chicago Fire Season 8 Episode 4, "Infection, Part I," is set to be out on Wednesday, Oct. 16, at 8-9 p.m. on NBC.