Una madre, víctima de un inexplicable ataque de rabia, comete un sorprendente acto de violencia y horror en el que, para mayor desconcierto, no tiene ni idea de por qué. El investigador se encuentra obsesionado con descubrir el motivo oculta de la mujer. Juntos viajarán por un viaje desgarrador hacia las profundidades de su psique y los violentos secretos escondidos en su pasado.

At first I thought the criminal was the Sinner.
So I was surprised that there’s three more seasons, because who is it once the mystery is solved?

It cuts both ways - the detective has a complex personality, not without reproach. He’s the sinner just as much as the criminals in the show.

This must be one of the best crime shows I’ve been watching for years. Wonderfully twisted plots that get untangled in a very satisfying way, as it should be in all procedurals.
I very much enjoy the psychological depth, the play with expectations, the depth of character, acting and story telling.

It wouldn’t be wrong to call this a psycho thriller, either. It touches personal fears. But there’s a resolution at the end.