One thing you should know about me is that I love “Kill List,” a sinister, unsettling British thriller released in the U.K. in 2011 and the U.S. in 2012. As off-the-rails as that movie gets, I love its audacity. Its director, Ben Wheatley, has followed it up with “Sightseers,” a morbid comedy that’s less ambitious but perhaps more conventionally entertaining. Because “Kill List” is dark, man.

Written by its stars, Alice Lowe and Steve Oram, both of whom had minor roles in “Kill List,” “Sightseers” is the story of a sheltered 34-year-old near-spinster named Tina who takes a camping vacation with her new boyfriend, Chris, whom her batty old mother doesn’t trust. It is revealed soon enough that Chris has some sociopathic tendencies — you would be wise not to litter in his presence — and the question is whether this behavior will bring out similar instincts in Tina, who’s timid but eager-to-please and harbors some untapped weirdness herself. (Her fascination with another camper’s dog is wonderfully bizarre.)

What follows is pitch-black and funny, nearly as dismal as “Kill List” but played for laughs rather than horror. Lowe and Oram’s natural performances are authentic and un-showy, like two ordinary people who happen to get involved in some casual bloodshed. By stripping away the usual trappings of movies about psychos — no longwinded explanations of why anybody does what they do — Wheatley lets us simply revel in the consequence-free mayhem.

B (1 hr., 28 min.; Not Rated, probably R for abundant harsh profanity, some very strong violence, some strong sexuality.)