The lady, whoever she was, was in a mask, such as ladies of high and low fashion wore at public places in those days, and had a male companion.

He was a lad of only seventeen, marvellously well dressed--indeed, no other than the Count's own son, Mr.Thomas Billings; who had at length received from his mother the silver-hilted sword, and the wig, which that affectionate parent had promised to him.
In the course of the month which had elapsed since the interview that has been described in the former chapter, Mr.Billings had several times had occasion to wait on his father; but though he had, according to her wishes, frequently alluded to the existence of his mother, the Count had never at any time expressed the slightest wish to renew his acquaintance with that lady; who, if she had seen him, had only seen him by stealth.
The fact is, that after Billings had related to her the particulars of his first meeting with his Excellency; which ended, like many of the latter visits, in nothing at all; Mrs.Hayes had found some pressing business, which continually took her to Whitehall, and had been prowling from day to day about Monsieur de Galgenstein's lodgings.

Four or five times in the week, as his Excellency stepped into his coach, he might have remarked, had he chosen, a woman in a black hood, who was looking most eagerly into his eyes: but those eyes had long since left off the practice of observing; and Madam Catherine's visits had so far gone for nothing.
On this night, however, inspired by gaiety and drink, the Count had been amazingly stricken by the gait and ogling of the lady in the mask.

The Reverend O'Flaherty, who was with him, and had observed the figure in the black cloak, recognised, or thought he recognised, her.

"It is the woman who dogs your Excellency every day," said he.