Leeched

Sixteen children, three vehicles, a farmhouse and thousands of leeches. Not the normal leeches. Aliens. They invaded, now they have to pay. At nine years old, Bailey and her friends ran away to her friend's farm to get away from the leeches that invaded their family's bodies. They lived peacefully, that was until one of their friends got kidnapped, then returned. What did the leeches do to that child? Where is her other friend?