The Glass Bird Girl (Knight's Haddon: Book 1)

Edie crouched on her bedroom windowsill, training her field glasses on the three boys by the stone pond.
Their names were Lyle, Jason and Tom, and she hated them. They were like foxes, thin and cunning, with eyes that flashed through mops of filthy hair.
It was nearly a month since Edie had come to live with her cousins at Folly Farm, and she had learnt to keep out of their way. If she wanted to know what they were doing, she spied. She peered down at them now, making a quick adjustment to her lens. Lyle, the eldest at thirteen, was holding a fishing net. His twin brothers watched as he thrust it into the middle of the pond, and stabbed it into the water. The stick started to bend and writhe and the others grabbed it too, three pairs of hands pulling the jerking net from the lilies.