There’s a word in the study of drama – catharsis – that describes the mixed emotions of pity and fear felt by an audience watching the main character’s freefall in a tragedy. Experiencing dramatic catharsis is supposed to be cleansing or therapeutic, since you leave the tragedy wiser and feeling better about your own life. Tatort: Borowski Season 3 has an episode worthy of this description. It’s about a character’s descent into criminality so shocking, so appalling, that you cannot turn away. It’s like watching a slow-motion car wreck. And like the audience of a Greek tragedy, you find yourself feeling cathartic relief that the disaster you’re watching isn’t yours.

Borowski and the Angel (Episode 6 in this season) shows a normal person – someone involved in one of the helping professions – who starts to make increasingly crazy, criminal decisions. How does that happen? Borowski’s question, posed to students in a class lecture, frames it all: “What makes criminals different from normal people?”

Sabrina Dobisch is an elder-care nurse who longs for excitement and attention. She watches old movies like a voyeur, envying the glamour and relational connection they represent. She observes a woman weeping over her dead cat in public and notes the attention she gets. The wheels start to turn… hey, she’s got a cat! She could get the same kind of attention over the death of her cat! So the descent begins.

To avoid spoilers, let’s just say the story takes you methodically into the mind of a sociopath. As Borowski says in his lecture, these folks seem perfectly normal. Most people cannot see the sociopaths around them because they blend in. The mystery is how they can rationalize the unthinkable and justify committing terrible acts. But good old Borowski does have eyes for sociopaths and smells something fishy about Sabrina’s story right away. He goes after her with unceasing, entertaining tenacity.

Kudos to the actress Lavinia Wilson playing Sabrina – she’s pitch perfect in portraying a woman with the face of an angel and the heart of a murderer. To me, this is one of the most gripping Tatort: Borowski episodes ever. Perhaps because it is so low-key, so understandable, so menacing. When you finish it, you’re relieved that you’re not Sabrina – you’re not a sociopath who goes around killing people, either accidentally or out of twisted thinking.

You hope.