The premise of four strangers showing up at a remote family cabin and giving them an impossible ultimatum is certainly an attention-grabbing setup rife with dramatic potential. However, Shyamalan's Knock at the Cabin fails to live up to that initial promise in several key ways.

For one, the characters are thinly drawn and not very compelling. We get only superficial backstories for the two fathers, Eric and Andrew, and their daughter Wen through brief flashbacks. This makes it difficult to emotionally invest in what happens to them.

The strangers, especially the large and intimidating yet strangely gentle Leonard, played by Dave Bautista, show more depth. Bautista is really the only performance that stood out in a good way. But the others, like Redmond and Sabrina, are basically just archetypes. We never get a real sense of who they are and why they are doing what they're doing beyond basic explanations. This hurts the suspense and intrigue of trying to figure them out.

Another issue is that once the initial premise is set up during the first act, the movie becomes rather plodding and drawn out. Scenes drag on with characters mainly just talking in circles about their situation. While the film tries to maintain an atmosphere of growing unease, much of the middle feels like it's treading water, waiting to get to the inevitable climax. There is a lack of rising dramatic stakes or revelations to continually engage the viewer.

Related to that, the film also struggles with maintaining a consistent tone. It wavers uncertainly between thriller, psychological drama, and quasi-biblical allegory without fully committing to any of them. This makes the overall viewing experience a bit choppy and disjointed, as the film never seems sure of its own identity. The characters also make plenty of random, odd choices that strain credibility at times just to further certain contrived plot points.

Finally, the conclusion is rather pedestrian and perfunctory, considering this is a M. Night Shyamalan film. Having grown accustomed to his patented shocking twist endings in the past, the rather straightforward climax here is a letdown. It provides no real payoff or thought-provoking twist to make the slog through the middling middle chapters feel worth it.

Ultimately, Knock at the Cabin was an unengaging way to spend 1 hour 40 minutes that I have little desire to revisit. With a stronger execution of its interesting concept, this could have been far more compelling, but as is, it's quite forgettable.