The spinoff miniseries The Walking Dead: Dead City brings back old characters and actors while introducing new cast members to further fill out the franchise. The Walking Dead: Dead City follows Negan (Jeffrey Dean Morgan) and Maggie Greene (Lauren Cohan) after the events of The Walking Dead as they travel to New York City to rescue Maggie’s son, Hershel (Logan Kim). Sometime between the end of The Walking Dead and the spinoff series, Hershel has been captured by “The Croat” and brought to New York City, which is completely overtaken by walkers and anarchist gangs.
https://screenrant.com/walking-dead-city-spinoff-cast-character-guide/