On the surface the movie has a simple plot. Two young women, sisters, are trapped inside of a pool, unable to leave while a thick fiberglass cover was put in place. However, the distressing situation turns heated when the two begin discussing their unresolved issues. Skeletons come out of the closet, teeth are bared, and hatchets are dug up for review! Before long though their predicament turns dire and a rogue third element is introduced which puts their love for each other to a test.
This is the epitome of a character driven story. It proves you don't need to have a large cast, expensive effects, or a heavy use of CGI to have a compelling story told. I found it to be wonderfully entertaining and well acted. I did lose a little interest about midway through, but this was likely because I had a hard time relating to any of the main characters, but towards the end I was firmly entrenched in seeing to their welfare.
Excellent job!