Basement Floor Finishing
Well the vapor barrier will help but it depends on a lot more. I have completed basements and below grade daylight basements that were / are totally dry without the plastic because the plastic would affect the grounding plane or uffer grounding system. The base of the slab had 6" to +12" of compacted rock then the wall footings or they were first also had at least 12" of rock and drain tubes around the foundation. Last we sealed the wall from the outside several different coatings in wet areas and heavy plastic sheeting from the siding down to the bottom then back filled with crushed rock. None of these leaked. On the wall line but one full basement did have water entry at a emergency window exit that a sump was added on the outside to keep from happening again. It all depends on how things were built. I have seen homes built over natural springs that were dry but other homes that were in a dry area on a hill leak like a some one was pumping water in. It all depends on how the home was prepared , and drained.  To tell the truth I don't see anything that works well from the inside if you have leakage , but if dry tape a plastic bag down on both the floor and walls. Wait 24 hours if the area looks damp maybe a sealer like epoxy paint may help but if water droplets I would be cautious unless you just had a 500 year rain storm.