Think of the Saw horror movie franchise and the most memorable thing about the films, apart from the villain Jigsaw, are the traps.
These are the devices that keep a person restrained as a timer counts down to a grisly, automated execution. The victim has to choose: slice off the trapped body part or die.
Actor and comedian Chris Rock struck a deal with the creative team behind the movie Spiral, the latest chapter in the franchise. He would keep to his lane and they would keep to theirs.
"We had an agreement early on that I would be in charge of the comedy and they would do the traps, the horror and the gore. Anything more than that would be egomania," says Rock, who is starring in, producing and has contributed to the story in the movie, the ninth instalment in the Saw series.
He was speaking at a recent online press conference.
The first movie, Saw (2004), was a breakthrough hit. It was the feature debut of Malaysia-born Australian film-maker James Wan, working with a screenplay by Australian writer and film-maker Leigh Whannell. The film was to be a launch pad to major Hollywood careers for both.
Spiral opens in cinemas today.
Rock, 56, is an unlikely A-list presence in what has typically been a low-to mid-budget horror series, albeit one with a strong fan following.
The cast has other notable names, such as Samuel L. Jackson and Max Minghella, actors of a stature not usually associated with a brand known for gore.
Rock says he became involved and helped steer the story towards a buddy-cop direction because, as a horror buff and fan of the series, he saw that he could help attract a wider audience without sacrificing its signature shocks.
"There're a lot of things in here for people who never watch horror. The comedy helps, the cast helps. Also, the relationships are really warm here - there's a dynamic between me, Sam and Max," he says.
Zeke, a detective played by Rock, and William, a rookie played by Minghella, investigate a series of horrific murders which indicate that the serial killer Jigsaw might still be alive.
Zeke's father, retired cop Marcus (Jackson), is drawn into the case.
Spiral pays homage to films such as buddy-cop movie 48 Hrs. (1982) and crime thrillers Reservoir Dogs (1992) and Seven (1995).
While it might be jarring for some to see Rock - whose career includes several stand-up specials and appearances in comedies such as Grown Ups (2010, with a sequel in 2013) - do drama in Spiral, it is not his first go at a non-comedy project. In the fourth season of the crime series Fargo, which aired last year, he played ruthless gang boss Loy Cannon.
"In the acting I've done, it's usually either-or: I'm either funny or I'm dramatic.
"There wasn't room to be funny in Fargo. Spiral's a welcome challenge because I get to do both. I set it up with the comedy then bring it home with the drama," he says.
Spiral director Darren Lynn Bousman is a series veteran, having directed the second (2005), third (2006) and fourth (2007) instalments.
Speaking to the press at another conference, he admits that Spiral's buddy-cop structure might seem odd to those familiar with the earlier films. But he reminds them that horror franchises such as Halloween or Nightmare On Elm Street have always enjoyed a freedom to go where other genres fear to tread.
"Jigsaw died in Saw 3, but he came back in Saw 4, 5, 6, 7 and 8. What's great about Saw is you never know where it's going to go. Maybe it's going to space next, I don't know," he says.
• Spiral opens in cinemas today.