The absolute best part of this movie was the acting from the main cast. Tenant, Condon, Sheehan, Byers, and Olivero were all great, and helped keep this movie from falling flat. For the most part, the writing was pretty good, if a bit cliched in some instances (Sean, the more-hero-than-antihero antihero, literally says "Take me, take me instead"). The storyline didn't push the plot very far out of a reasonable realm of possibility, which made it that much more compelling.
This is a long review, and you will likely finish it by thinking I hated the script. I don't hate the script, and most of it was honestly pretty well done. That being said, I have several issues with the movie that didn't ruin it for me, but not for lack of trying.
First and biggest of the issues is the role of law enforcement in this movie. The only police officer we get to know at all seems competent, if weary and cookie cutter, and even has a scene where he's questioning Cale (Tennant) in the house where the girl was supposed to have been tied up that gives all the telltale signs that he's starting to suspect something, but is savvy enough to play it off in the moment. This is apparently a wrong impression, as he immediately afterward all but accuses Sean (Sheehan) of stalking and harassment. This was very much a ludicrous turn, as Cale is very obviously lying, the cop gives all the signs of coming to the same conclusion during the interview (including the whole "Oh yeah, one more thing" thing that suspicious cops do in the movies), and then goes the complete other way.
The FBI also gets involved, as the aforementioned cop directs Sean to them to file a missing persons report (which seems odd, as I'm 95% sure police do that as well), and each and every one of them sounds like their lines were written by running every CSI episode through an algorithm that finds bland dialogue and then makes it worse. They were at best phoned in, and frankly, the plot didn't even need them. They filled in gaps, that were entirely unnecessary to know, of Cale's background, and arrested him at the end, his having already been thoroughly subdued by Sean and Katie (Condon) to the point that they became almost a redundancy.
Secondly, the plot does not have a satisfactory resolution. Yes, the bad guy gets caught, the captive girl gets saved, and we can assume that everything else went fine after that. But that isn't good enough. My main issue with this is that Sean's girlfriend, Riley (Byers), is in the hospital on a ventilator (more on that in a bit), and hates him for things that were not his fault. We can assume that things are resolved between them, but we have absolutely no way of knowing that. While this isn't necessarily a problem, the way it was handled is. There's a certain feel to a scene that is given by all the techniques of storytelling and filmmaking that tell you what to expect in that arc of the plot. The way the plot with Riley was told, the hospital scene expected a resolution that was to come, that never came. There is no ending of that arc, and it's clear (as there's no reason for it) that this wasn't intentional, it was just bad story telling. I was caught off guard by the end of the movie because I was expecting that resolution, and as I'm entirely sure they weren't just leaving it for the sequel, that's not a great thing to leave the audience with.
Lastly, some plot point questions and grumbles:
1) Riley gets her head smashed into a brick wall twice, and then is thrown down some stairs, landing on her back/neck. She is later seen in the hospital, when Sean goes to visit her to try and explain things. She is conscious, with no neck brace, is able to freely move her head, and is of a mental and physical capacity to reach for and write normally upon a notepad. She's also hooked up to a ventilator, implying that her trauma made it hard for her to breathe. All of that combined seems immensely implausible, especially as it's indicated that Sean would've gotten to her within a few hours of the incident, having been summoned by a call from her phone made by someone going through her emergency contact list. Came across as lazy writing.
2) Cale blows up his house after setting a trap for Sean, who he (correctly and reasonably) assumed would come back after seeing Riley in the hospital. He does this by turning on his gas stove, letting it spread through the house, and setting up a bomb in his oven with a timer, and remotely locking all of the doors once Sean is in the house. A few points on this: Sean gets in through a window, which is not remotely controlled, and could easily be used again, though it isn't; if you're a bad guy trying to get away and possess a sophistaced level of smart home functionality, setting up a bomb instead of just an innocuous ignition source, seems poorly planned; if you're a bad guy trying to trick someone into a house that's going to blow up, you probably don't want to give away the game with more than 30 seconds to go before the explosion, nor would you put a bomb with a timer that's easily visible and inherently gives useful information to your would-be victim; where did Cale get sticks of dynamite, and who makes bombs that look like something a Looney Toons cartoon would have? It's just silly on its face.
All in all, I think that someone had a good idea for a movie, had some genuinely good ideas for making the script come to life, and then filled in the gaps with whatever came to mind first. So, good, but not great, and a little disappointing on reflection. It had a lot going for it in cast and general plot, but the little bits hold it back.
This is a long review, and you will likely finish it by thinking I hated the script. I don't hate the script, and most of it was honestly pretty well done. That being said, I have several issues with the movie that didn't ruin it for me, but not for lack of trying.
First and biggest of the issues is the role of law enforcement in this movie. The only police officer we get to know at all seems competent, if weary and cookie cutter, and even has a scene where he's questioning Cale (Tennant) in the house where the girl was supposed to have been tied up that gives all the telltale signs that he's starting to suspect something, but is savvy enough to play it off in the moment. This is apparently a wrong impression, as he immediately afterward all but accuses Sean (Sheehan) of stalking and harassment. This was very much a ludicrous turn, as Cale is very obviously lying, the cop gives all the signs of coming to the same conclusion during the interview (including the whole "Oh yeah, one more thing" thing that suspicious cops do in the movies), and then goes the complete other way.
The FBI also gets involved, as the aforementioned cop directs Sean to them to file a missing persons report (which seems odd, as I'm 95% sure police do that as well), and each and every one of them sounds like their lines were written by running every CSI episode through an algorithm that finds bland dialogue and then makes it worse. They were at best phoned in, and frankly, the plot didn't even need them. They filled in gaps, that were entirely unnecessary to know, of Cale's background, and arrested him at the end, his having already been thoroughly subdued by Sean and Katie (Condon) to the point that they became almost a redundancy.
Secondly, the plot does not have a satisfactory resolution. Yes, the bad guy gets caught, the captive girl gets saved, and we can assume that everything else went fine after that. But that isn't good enough. My main issue with this is that Sean's girlfriend, Riley (Byers), is in the hospital on a ventilator (more on that in a bit), and hates him for things that were not his fault. We can assume that things are resolved between them, but we have absolutely no way of knowing that. While this isn't necessarily a problem, the way it was handled is. There's a certain feel to a scene that is given by all the techniques of storytelling and filmmaking that tell you what to expect in that arc of the plot. The way the plot with Riley was told, the hospital scene expected a resolution that was to come, that never came. There is no ending of that arc, and it's clear (as there's no reason for it) that this wasn't intentional, it was just bad story telling. I was caught off guard by the end of the movie because I was expecting that resolution, and as I'm entirely sure they weren't just leaving it for the sequel, that's not a great thing to leave the audience with.
Lastly, some plot point questions and grumbles:
1) Riley gets her head smashed into a brick wall twice, and then is thrown down some stairs, landing on her back/neck. She is later seen in the hospital, when Sean goes to visit her to try and explain things. She is conscious, with no neck brace, is able to freely move her head, and is of a mental and physical capacity to reach for and write normally upon a notepad. She's also hooked up to a ventilator, implying that her trauma made it hard for her to breathe. All of that combined seems immensely implausible, especially as it's indicated that Sean would've gotten to her within a few hours of the incident, having been summoned by a call from her phone made by someone going through her emergency contact list. Came across as lazy writing.
2) Cale blows up his house after setting a trap for Sean, who he (correctly and reasonably) assumed would come back after seeing Riley in the hospital. He does this by turning on his gas stove, letting it spread through the house, and setting up a bomb in his oven with a timer, and remotely locking all of the doors once Sean is in the house. A few points on this: Sean gets in through a window, which is not remotely controlled, and could easily be used again, though it isn't; if you're a bad guy trying to get away and possess a sophistaced level of smart home functionality, setting up a bomb instead of just an innocuous ignition source, seems poorly planned; if you're a bad guy trying to trick someone into a house that's going to blow up, you probably don't want to give away the game with more than 30 seconds to go before the explosion, nor would you put a bomb with a timer that's easily visible and inherently gives useful information to your would-be victim; where did Cale get sticks of dynamite, and who makes bombs that look like something a Looney Toons cartoon would have? It's just silly on its face.
All in all, I think that someone had a good idea for a movie, had some genuinely good ideas for making the script come to life, and then filled in the gaps with whatever came to mind first. So, good, but not great, and a little disappointing on reflection. It had a lot going for it in cast and general plot, but the little bits hold it back.