In the upcoming episode of "Chicago Fire," titled "Post Mortem," Chief Boden, played by Eamonn Walker, will make a return in a unique storytelling format involving flashbacks and different perspectives. Boden will lead a team in investigating a deadly fire that resulted in a firefighter's death. The episode will focus on a post-mortem investigation led by Boden, showcasing his expertise and leadership skills. Fans can look forward to seeing Boden in action once again, following his departure from Firehouse 51 in a previous season.
Source: https://www.looper.com/1805530/eamonn-walker-wallace-boden-chicago-fire-season-13-return-explained/