It has been eight years since “Hostel: Part II,” and the phrase “directed by Eli Roth” has been largely absent as the horror filmmaker has focused more on producing and acting, but 2015 saw him return to the director’s chair with a vengeance. First, he gave us the cannibal horror film “The Green Inferno” which saw its release delayed for a couple of years, and he quickly followed it up with the home invasion thriller “Knock Knock.” Keanu Reeves stars as Evan Webber, an architect and happily married husband and father whose family leaves him alone at home one weekend so he can work on his latest project. But Evan soon makes the biggest mistake of his life when he lets two young women into his home after they claim to be lost, and they come to play a number of psychosexual games which have him begging for his life.

Roth was at the Four Seasons Hotel in Los Angeles, California to do a press conference on “Knock Knock,” and he was very verbose in discussing what motivated him to make this film. Now whereas his previous movies “Cabin Fever,” “Hostel” and “The Green Inferno” featured young adults heading out of their comfort zones and into the world for a dose of excitement and danger, “Knock Knock” is very different in that it rarely strays from Evan’s comfort zone which is his home. I asked Roth if this scenario presented any new challenges for him as a writer, and his answer was far more descriptive than I expected.

Eli Roth: No, I mean I liked the idea. Obviously I was very interested, probably because I grew up in Massachusetts with that kind of over sheltered, over-privileged and overeducated upper middle-class kid image that yearns for that life experience. In “Cabin Fever” they want irresponsible partying and drinking and drugs, in “Hostel” they want sex they think they can’t find, and in “The Green Inferno” they want validation through this vanity act and they want Twitter followers and it all comes back to bite them in the ass, literally in “Green Inferno.” But with this one, it is about what happens when you let that force into your life that you’re suddenly like, oh my God there’s a crazy person in my house. What have I done? You realize that, because you’re smart, that’s actually what makes you vulnerable. You think well I know how to handle this situation because I’m a smart person and look how well I’ve done so far, and then you drop your guard and then maybe there is some situation where someone’s in your home for whatever reason and you realize, oh my God, this person could take my stuff. There are my alarm codes and they could just really unravel me, and they could do it in such a short amount of time. And then Nicolas (Lopez) and I decided to add the social media aspect. We also were interested in the generational difference in sexuality. Girls in their teens or their 20’s, they must be so much crazier because of internet pornography. There is this grass is always greener mentality and looking at the way teenagers sexualize themselves on Instagram for likes and follows, we’re looking at some people like, in the cast and crew, their young sisters that are 15 or 16 and looking at their friends. You can’t tell in your 40’s if that girl is 16 or 36, and I’m playing on that difference of the sexuality in generations. Now nothing is private anymore, so when we were writing it we just thought about all of the things about modern fears. I wrote “Cabin Fever” when I was 22, I wrote “Hostel” when I was 32, and I wrote “Knock Knock” when I was 42, so they are all very much written about my fears at those ages.

Well, whether he is directing a movie or just producing or acting in one, Roth is certainly not a filmmaker you should ever call lazy. He remains as prolific as ever, and he has a large number of projects he is working on. Among them is “Meg,” an adaptation of Steve Alten’s science fiction novel about an ancient 60-foot long shark which terrorizes a small coastal town. Some critics have described the book as the “Moby Dick” of killer shark novels, so it will be interesting to see Roth’s take on it.

“Knock Knock” is now available to own and rent on DVD, Blu-ray, and Digital.