“Dangerous Animals,” the new horror film out of Australia, starts with a cheekily fun cold open. A pair of tourists decide they want to swim with sharks so they seek out a sketchy looking attraction run by Tucker, a boisterously bearded Jai Courtney.

Director Sean Byrne has a blast playing around with Tucker’s deceptive good nature, using quick cuts to up the tension. To calm down one of his nervous customers this intensely jolly boat captain launches into a rendition of “Baby Shark.”

But quickly you discover that despite the sing-along Tucker has no redeeming qualities, and as the movie digs into his dark side it becomes a repetitive throwback torture porn that lurches toward an inevitable conclusion. Tucker, a serial killer, has a creative way of killing his victims, but that’s about as clever as the film gets.

One of the reasons “Dangerous Animals” feels so stale...