Why does kira want to believe the beasts in the woods, what sound does she hear at night, when they investigate the noise, what do they discover it...

Kira has been told all of her life that the beasts live in the woods and were the ones who had killed her father.  She has been taken in by Jamison and lives in his quarters along with Thomas, a wood carver.  At night they hear a strange noise.  They wonder if it is the beasts but later they hear crying.  Kira investigates and finds Jo, a little tyke who has bee taken from her parents who died.  Jo is locked up and does not know that her mother is dead.

The beasts really do not exist which will be revealed later in the story.  Kira learns that they have all lost their parents possibly to murder so that the elders could contain their gifts and control their future by making them create what they want.

There is also an incidence when she hears stirrings in the woods.  We later learn that these are broken people who remove people from the forest where they are laid to die or after they are dead.  One of those people was Kira's father whom they rescued.