Still, they had in common their youth, their boredom, their high spirits and their hunger for amusement; and Undine was making the most of these ties when one day, coming back from a trip to Monte-Carlo with the Princess, she was brought up short by the sight of a lady—­evidently a new arrival—­who was seated in an attitude of respectful intimacy beside the old Duchess’s chair.  Undine, advancing unheard over the fine gravel of the garden path, recognized at a glance the Marquise de Trezac’s drooping nose and disdainful back, and at the same moment heard her say:  “—­And her husband?”

“Her husband?  But she’s an American—­she’s divorced,” the Duchess replied, as if she were merely stating the same fact in two different ways; and Undine stopped short with a pang of apprehension.

The Princess came up behind her.  “Who’s the solemn person with Mamma?  Ah, that old bore of a Trezac!” She dropped her long eye-glass with a laugh.  “Well, she’ll be useful—­she’ll stick to Mamma like a leech and we shall get away oftener.  Come, let’s go and be charming to her.”

She approached Madame de Trezac effusively, and after an interchange of exclamations Undine heard her say “You know my friend Mrs. Marvell?  No?  How odd!  Where do you manage to hide yourself, chere Madame?  Undine, here’s a compatriot who hasn’t the pleasure—­”

“I’m such a hermit, dear Mrs. Marvell—­the Princess shows me what I miss,” the Marquise de Trezac murmured, rising to give her hand to Undine, and speaking in a voice so different from that of the supercilious Miss Wincher that only her facial angle and the droop of her nose linked her to the hated vision of Potash Springs.

Undine felt herself dancing on a flood-tide of security.  For the first time the memory of Potash Springs became a thing to smile at, and with the Princess’s arm through hers she shone back triumphantly on Madame de Trezac, who seemed to have grown suddenly obsequious and insignificant, as though the waving of the Princess’s wand had stripped her of all her false advantages.

But upstairs, in her own room.  Undine’s courage fell.  Madame de Trezac had been civil, effusive even, because for the moment she had been taken off her guard by finding Mrs. Marvell on terms of intimacy with the Princess Estradina and her mother.  But the force of facts would reassert itself.  Far from continuing to see Undine through her French friends’ eyes she would probably invite them to view her compatriot through the searching lens of her own ampler information.  “The old hypocrite—­she’ll tell them everything,” Undine murmured, wincing at the recollection of the dentist’s assistant from Deposit, and staring miserably at her reflection in the dressing-table mirror.  Of what use were youth and grace and good looks, if one drop of poison distilled from the envy of a narrow-minded woman was enough to paralyze them?  Of course Madame de Trezac knew and remembered, and, secure in her own impregnable position, would never rest till she had driven out the intruder.