I'm not entirely sure as I haven't read it specifically. But generally, it might be about the adventures of Emil and some detective - like elements. Maybe Emil gets involved in solving mysteries or has some exciting encounters in a city or town setting.
Since I don't have access to the 'emil und die detektive graphic novel', we can only guess. Obviously, Emil is probably a main character. There may be a group of kids or adults who join him on his detective adventures. There could be a wise old man or woman who gives them clues or advice. And there might be a villain or two who are causing trouble in the story. It's also possible that there are some side characters like shopkeepers or policemen who interact with Emil and the other main characters and help move the story along.
Homelander does die in the Boys comic. It happens due to a combination of factors including his own actions and the opposition he faces from other characters.