Abandoned (2015)

Single mom Streak takes a job as a night time security guard at an abandoned high-rise building.  On her first night on the job, she's told that she will patrol the building at regular intervals while her partner - a grumpy middle aged man in a wheelchair - watches the security monitors and communicates over the radio to her.

Before her manager leaves for the night, he makes it clear that no one is allowed in, and if someone does get in, her job is to get them out.  Streak is desperate for this job. She needs this job as she's worried that she's going to lose custody of her daughter and this appears to be her last chance of avoiding this.

This is why it's so crazy when a few hours later, and against her partners instructions, Streak lets a homeless man in to spend the night because there's a storm outside. Argh! Sure, come on in crazy homeless guy and bring your dog too.

As if that isn't a bad enough decision, she is told to stay away from the part of the building where there are no cameras. But she wants to figure out why the cameras don't work and heads into the basement to fix them. While there she hears something behind a padlocked door. What is a new employee to do on their first day? Obey the rules and continue your rounds, or break the padlock off the old door and explore? Streak decides it's padlock breaking time and off she goes.

Oh Streak, don't you understand that they've hired you to keep people out?  Even if someone is in there, the padlock keeps them out. Now she's opened up an avenue for anyone in there to come into the building. And if your employer has a padlocked door, it's not a good idea to break the lock and explore, ever.

Strange things start happening, and Streak sees little kids in the labyrinth behind the padlocked door.  Is it real? Is she crazy?  Will there be a payoff at the end? No, no there won't. The ending will annoy the hell out of you as it's totally unsatisfactory.