"But where is Sonya ?" She looked round and seeing that her friend was not in the room ran to look for her.
Running into Sonya's room and not finding her there, Natasha ran to the nursery, but Sonya was not there either.

Natasha concluded that she must be on the chest in the passage.

The chest in the passage was the place of mourning for the younger female generation in the Rostov household.
And there in fact was Sonya lying face downward on Nurse's dirty feather bed on the top of the chest, crumpling her gauzy pink dress under her, hiding her face with her slender fingers, and sobbing so convulsively that her bare little shoulders shook.

Natasha's face, which had been so radiantly happy all that saint's day, suddenly changed: her eyes became fixed, and then a shiver passed down her broad neck and the corners of her mouth drooped.
"Sonya! What is it?
What is the matter ?...

Oo...