As the dwarves are fighting the trolls, Sawril watched from the treetop, and watched Bilbo manage to steal a knife and free the ponies. She could feel herself being proud of the Hobbit's courage. However, the trolls noticed him and they each grabbed him, holding him by his arms and legs. 

"Lay down your arms! Or we’ll rip his off!"

The she-elf narrowed her eyes at their actions, and crouched down upon the tree, balancing herself as she crawled like a cat stalking its prey, moving from her hiding place and onto a rock behind the trolls. Unintentionally, she saw Gandalf. Where has he been?