Mysterious beach vacation

Summer, sun. You friends decided to spend a free day at the beach to get away from the stuffy room and plenty to enjoy a swim in the sea. But, it is not as you imagined it. From the beginning, once you have stretched blanket on the sand, you have something disturbing, and it seems that is not in vain. World around him changed, everything is blurred. What's the obsession? What the letters around you fly? We need to understand!