Du Tillet's speech brought her fears to a point; she dreaded lest all should be discovered; she knew her sister's signature was in Nucingen's hands, and she resolved to entreat Marie to save herself by confessing all to Felix.
She drove to her sister's house, but Marie was not at home.

Felix was there.

A voice within her cried aloud to Eugenie to save her sister; the morrow might be too late.

She took a vast responsibility upon herself, but she resolved to tell all to the count.

Surely he would be indulgent when he knew that his honor was still safe.