His first big case is the bizarre murder of the Hazlitt family, who have ties to the church of a Sister Molly (Kerry Biche), a popular, winsome evangelist. The corpses are made up like Day of the Dead figures and lead Vega and his world-weary partner, Lewis Michener (Nathan Lane) further into the insurgent Mexican-American culture rising in the city, circa 1938.

Zovatto, 28, spoke to The Post from LA.

I wasn’t expecting all the Day of the Dead mysticism in the first episode. Santiago’s mother (Adriana Barza) has an altar to Santa Muerte (Lorenza Izzo), the Angel of Holy Death, in her home.  Were you familiar with that?
Being from Costa Rica and having Mexican friends throughout my life, I was aware of Santa Muerte and the Day of the Dead and the significance of that. And the way that it carries through the culture. [Creator] John Logan put his own spin on it.

I was also surprised to see Nazis having a rally in Pershing Square. Is that based on fact?
There were places in the mountains by Malibu where they held ceremonies and the whole Peter Craft {Rory Kinnear) element of the story. The show follows the history but it is also imagined by John Logan.

What are viewers to make of Santiago’s involvement with Sister Molly, the evangelist?
Molly and Tiago find themselves in this mutual land where they can say things to each other that they don’t usually say to anybody else. It’s a mirror relationship and they find peace within that. At the same time, their worlds collide with the Hazlitt murder and from there the story goes places.

What is Santiago’s motivation for becoming a detective?
He’s the one who went as far as he could from his lineage, [being] Latino, being a minority. One of the most beautiful scenes, in my opinion, is when he’s working in the fields with his dad and he’s trying to save him from a fire. That was a turning point. Santa Muerte pushed him away. And Tiago’s mother said, “You’re just the first one to help the next one up.”

What was it like to work with Nathan Lane?
Amazing. When I was a kid, I grew up with his movies like “The Lion King.” He did a play called “The Nance” when I lived in New York, and I thought, “I’d love to work with this guy someday.” He’s also playing something I’ve never seen him play before — an old cop who’s been on the force a long time and who’s going through a lot. It was awesome to see that, front row.

“Penny Dreadful: City of Angels” airs Sunday at 10 p.m. on Showtime