The day Lucy Liu arrived on the set of Luke Cage things got a little complicated. Netflix’s superhero caper is filmed on location in Harlem and locals weren’t slow about voicing their enthusiasm for the Charlie’s Angels star, there in the unfamiliar role of TV director.

Selfies were requested, in such numbers that Liu had to politely point out that, along with meeting her public, she was in Harlem to do a job. She was overseeing the first episode of Luke Cage’s long-awaited second season. If it was okay with the well-wishers, she needed to get on with it.

One reason Liu was anxious to proceed was that she had to choreograph several brutal fight scenes. Luke Cage (The Good Wife’s Mike Holter) is indestructible – an almost literal man of steel. This places a particular demand on a director. How do you make the stakes seem real, given Cage cannot be harmed by normal means?

“We really collaborated on everything,” says Liu of working with the show’s writer, Cheo Hodari Coker. “It’s not just a case of ‘instead of using that couch, let’s use this couch’. We had to choreograph the fight scenes and study them very closely. And of course then we had a paparazzi following us. We had to tell him to get out of the show.”

Liu enjoyed her foray into the Marvel universe – hers is one of seven Luke Cage episodes overseen by female film-makers in the second series – but grateful, too, for where her responsibilities ended.

“As director you get to collaborate with the writers,” she says. “As the show-runner, you’re dealing with a lot of other pressures – scripts to be prepped, trying to be on set even as you’re prepping. It’s a difficult place.”

Coker, though, seems very much up for the challenge. He shepherded Luke Cage series one to screen in 2016, the stampede to watch causing Netflix to temporarily go on the blink (Coker likes to joke that he’s the guy who “broke Netflix”).

Cage’s success proved, moreover, that there was room for a black superhero in the mainstream. The appetite for more diverse costumed crusaders has since been proved beyond question by Black Panther. But Luke Cage, and Coker, were there first.

“We don’t water down culture at all,” says Coker during a public interview earlier in the day. “It’s done in such a way that even if you’re not from hip hop culture or African American culture; there’s a window into the show. The thing I love about the worldwide reception is that a lot of people who aren’t from the African American experience connect with the show, so it proves people around the world just want a good series.”

Coker is in many ways an unlikely saviour of the superhero genre. He began his career as a music journalist (he was an early champion of Notorious B.I.G.) and says that his ultimate goal in life was to become an A&R man. Instead he got into TV, starting with the LA crime drama Southland, before graduating to Netflix and Luke Cage.

Nonetheless, his early instincts as a hustling music writer endure. Coker explains that he sequences a new season like a classic album – he has variously likened Luke Cage series two to the later works of A Tribe Call Quest and to Miles Davis’s Bitch’s Brew. And he regards binge-watching as the equivalent to rushing to the record store for the latest Prince LP. Each episode, he elaborates, starts out as a script named for a song on the soundtrack (the present run includes includes Ghostface Killah, Faith Evans and Esperanza Spalding).

The purest manifestation of this is new antagonist Bushmaster (Mustafa Shakir), whose Caribbean background gives Coker licence to celebrate his love of reggae and dub.

“The Jamaican culture is the culture of resistance,” says Coker. “A culture of pride. It is a very complex island. What was interesting about Bushmaster is that now you have these two warring factors – the Jamaican perspective and the [African-American] one. There’s a post-slavery tension there. But it’s still a superhero story – good guys and bad guys with special powers. The idea is to just do it all if you can.”

Cage is never the most gung-ho of superheroes. However, he goes to some especially dark places in the second season. The question with which the series is wresting is how far a hero can descend before they are virtually identical to the villains they are trying to neutralise.

“If you control crime, does crime control you?” muses Coker. “Are you a crime boss? It gets to the point where the easiest way to solve the Bushmaster problem is to take over. I’m going to get into trouble referencing DC [Marvel’s bitter foes]… but what’s to stop Superman from snapping someone’s neck? What prevents Batman from just killing the Joker.”

Portraying Cage in an unflattering light challenges some of the basic assumptions about superheroes – a delicious twist that ensures Luke Cage season two is compelling all the way to the end.

“Mike Tyson had a saying that everybody’s got a plan until they get punched in the face,” say Coker. “That’s kind of the metaphor for Luke, because you finally have somebody that can knock him down in Bushmaster. When you are at the wrong end of a big defeat, how does it affect you? Does it impact your psyche?

• Luke Cage Season 2 is out now.