"I am sure Mr.Warrington is a gentleman, if you are not.

Perhaps I have no finger prints to correspond with those on the bottle.

If not, I am sure that we can send for some one whose prints will do so." She was studying the bottle.
"The other, however," she said slowly to conceal her own surprise, "was a person who has been set to trail you and Stella, Mr.Warrington, a detective named Drummond!" Suddenly the truth flashed over her.

Drummond was not employed by Mrs.
Warrington at all.

Then by whom?
By the directors.