The Spy in Black by J. Storer Clouston

I woke on Wednesday morning with an outlook so changed that I felt as if some magician must have altered my nature. Theoretically I had taken a momentous and dangerous decision at the call of duty, and all my energies ought to have concentrated on the task of carrying it through safely, thoroughly, and warily. I had need of more caution than ever, and of the most constant vigilance -- both for the sake of my skin and my country. As a matter of fact I was possessed with the recklessness of a man drifting on a plank down a rapid, where taking thought will not serve him an iota. In vain I preached theoretical caution to myself -- exactly how vainly may be judged by my first performance in the morning when I found myself alone with Eileen in the parlour. She suggested that for my own sake I had better be getting back to my room.

"Will you come and sit there with me? " I asked.