Complex sentence: Jim returns to work as a police detective in Gotham City and the rage filled Jim was performing his duties as The Spectre by practicing vengeance rather than Justice until Phantom Stranger attacked his police precinct convinced he was the one who kidnapped his family out of revenge.
Split into simpler sentences: Jim returns to work as a police detective in Gotham City. The rage-filled Jim was performing his duties as The Spectre by practicing vengeance rather than justice, until Phantom Stranger attacked his police precinct, convinced he was the one who kidnapped his family out of revenge.