Walker’s Wallace Boden was last seen onscreen in the season 12 finale

Eamonn Walker is back on Chicago Fire for one night and one night only.

The beloved actor, 62, who exited the series after 12 seasons as a series regular last May, will reprise his role as Wallace Boden, who is now First Deputy Commissioner of the Chicago Fire Department, in an April 16 episode.

The episode will see Boden “tasked by Commissioner Grissom (Gary Cole) to run a post-incident analysis following a house fire that collapsed with a firefighter inside.”

In a statement, showrunner Andrea Newman said they’re “so excited to have our beloved Chief Boden back, and the episode, titled ‘Post-Mortem,’ is a thrill ride unlike any we’ve done before.”

She continued of what’s to come, “Told with flashbacks and unique POVs, Chief Boden leads our team on a search to discover the how, who, and why of a fierce firefight that ended in disaster.”

Walker last appeared on Chicago Fire in the season 12 finale, which aired on May 22. His exit was explained by his character’s promotion from Chief to Deputy Commissioner of the city’s fire department.

He was succeeded by newcomer Dermot Mulroney, who joined the cast as Chief Dom Pascal in season 13.

Mulroney, whose character returned to Chicago after a stint as chief in Miami, said on the Today show in October that it’s been “great to join a popular series” with an “incredible cast that are so close with each other.”

“It’s amazing. First of all, it’s nice to have a steady job for once. Thank you, NBC, for that. What took so long?” he joked, calling the “well-run” show “an education every day.”

Season 12 was full of shake-ups for Chicago Fire, as Kara Killmer exited after nearly 10 years on the series and Taylor Kinney returned after taking a leave of absence to deal with a “personal matter,” a source close to production told PEOPLE at the time.