Read "The Stretton Street Affair" by William le Queux online for free on Textopian. Full text with search, annotations, highlights, and AI-powered reading aids.
Having decided to still remain in Madrid I deemed it advisable to engage the services of a private inquiry agent to watch the movements of De Gex and Suzor, who still remained at the Ritz. The mystery-man, living under an assumed name, never went out in the daytime, though Suzor often went forth, paying visits to certain banks and commercial offices in connexion with the proposed new railway.
The man we engaged was an elderly ex-detective of the Seville police, named Pardo, who very soon discovered the identity of the secret agent employed to keep surveillance upon De Gex on behalf of the police so that no harm should befall him.