The first season of “Serial,” the explosively popular podcast from investigative reporters Sarah Koenig and Julie Snyder, told the story of Adnan Syed and Hae Min Lee, the 18-year-old high school student murdered and left in the woods of Maryland. Syed, her ex-boyfriend, was found guilty of her murder and sentenced to life plus 30 years. After the series aired, he succeeded in getting a retrial. That’s set to commence in December. In the second season, Koenig and Snyder took on the bizarre case of Bowe Bergdahl, the army private who burst into the national consciousness when the Taliban traded him for Guantanamo prisoners; Bergdahl was eventually tried for desertion and dishonorably discharged from his post.

In the third season of “Serial,” Koenig tells the stories of the veryracist tropes about broken black families and drug use. He also tries to coerce a man into a guilty plea by threatening to stack multiple 14-year sentences.

There’s the top brass in the Cleveland police fighting reforms, even after a rookie cop shot 12-year-old Tamir Rice as he played in a park. Koenig has a maddening exchange with Steve Loomis, the former head of the Cleveland police union, who refuses to budge from his position that shooting Rice was the right thing to do.

The series ably illustrates structural problems that bedevil the system, even when the intentions are mostly good. For example, while probation might seem like a more humane alternative to jail, in reality it can entrap defendants in a never-ending power struggle with the court — one