In The Onyx Lobby by Carolyn Wells — Read

When Richard set out to do a thing, he did it, and without consulting anybody he went at once for Pennington Wise, the detective, and by good luck, succeeding in obtaining the services of that astute investigator.

Bates told him the whole story, and Wise saw at once that though the young man was fearful of his aunt's implication in the matter, he was even more alarmed at the idea of his sweetheart's mother being brought into it.