芝加哥警署第21辖区分为两个部分，包括直接打击犯罪的行动组和负责调查城市之中犯罪团伙的情报组。汉克（杰森·贝吉 Jason Beghe 饰）是情报组的组长，他嫉恶如仇，将打击犯罪当做自己义不容辞的首要任务，在他英明果断的决策下，许多穷凶极恶的犯罪分子一一落网。 安东尼奥（乔恩·塞达 Jon Seda 饰）是汉克手下的一员要将，尽管他曾经和汉克有过一段不太愉快的过去，但他依然将在汉克手下工作当做是一种光荣。其他身在行动组的组员们亦是如此，能够跻身成为情报组中的一员是他们梦寐以求的事情。然而，情报组的工作谈何容易，加入了情报组，就以为这要和芝加哥最邪恶、最凶残的罪犯展开正面交锋。
To the streets, “Raq” Thomas is cold, hard and fierce — a successful and deadly woman taking names in a man’s world. She is tough, resolute, ruthless, but Raq still is capable of love. Great love. The sole recipient of that affection is her son, Kanan; he is everything to her. As much as she cares for him, though, there are many instances where one wonders if she loves him for who he is or if she loves him merely as an extension of herself. The middle child of three, Raq also carries the heavy burden as the earner for her two brothers. She is the sun, and everyone else in her universe exists in her orbit.
