She had to get out of the room, or die.
Just then Jack walked back in.

For a few moments she had forgotten Jack.

The terror arising from the menace upstairs returned to her.
But Jack's happy face was assurance that as yet he knew nothing of the second Matilda.
Yes, she had to get out, or die.

And Jack's reappearance gave her frantic mind a cue for an unbetraying exit.
"I'll go to the kitchen--and start supper," she gulped, and hurried into the butler's pantry.
"Jack," she heard Mary's perplexed voice, "Matilda, somehow, seems rather queer to me." "She doesn't seem quite herself," agreed Jack.
Mrs.De Peyster sank into a chair beside the door, and sat there motionless, hardly daring to breathe--shattered by the narrowness of her escape, and appalled by this new situation that had risen around her--too appalled even to consider what might be the situation's natural developments.

Soon amid the wild churning of various emotions, anger began to rise, and outraged pride.