Black Coffee by Agatha Christie

that Sir Claud took certain precautions to prevent the formula from being removed from this room. When he sprang his little surprise and announced our imminent arrival, it is quite certain, therefore, that the thief still had the formula on his person. What must he do? He dare not risk having it found on him when I arrived. He can do only two things. He can return it, in the manner suggested by Sir Claud, or else he can hide it somewhere, under cover of that one minute of total darkness. Since he did not do the first, he must have done the second. Voilà! It is obvious to me that the formula is hidden in this room.”
    “By God, Poirot,” Hastings exclaimed in great excitement, “I believe you're right! Let's look for it.” He rose quickly, and moved to the desk.
    “By all means, if it amuses you,” Poirot responded. “But there is someone who will be able to find it more easily than you can.”
    “Oh, and who is that?” asked Hastings.
    Poirot twirled his moustache with enormous energy.
    “Why, the person who hid it, parbleu!” he exclaimed, accompanying his words with the kind of gesture more suitably employed by a magician pulling a rabbit out of a hat.
    “You mean that -”
    “I mean,” Poirot explained patiently to his colleague, “that sooner or later the thief will try to recapture his booty. One or the other of us, therefore, must constantly remain on guard -” Hearing the door being opened slowly and cautiously, he broke off and beckoned Hastings to join him by the gramophone, out of the immediate sight of anyone entering the room.

Black Coffee

Chapter 10
    The door opened, and Barbara Amory entered the room cautiously. Taking a chair from near the wall, she placed it in front of the bookcase, climbed on it, and reached for the tin case containing the drugs. At that moment, Hastings suddenly sneezed, and Barbara, with a start, dropped the box.
    “Oh!” she exclaimed in some confusion. “I didn't know there was anyone here.”
    Hastings rushed forward and retrieved the box, which Poirot then took from him.
    “Permit me, mademoiselle,” said the detective. “I am sure that is too heavy for you.”
    He moved to the center table and placed the tin case upon it. “It is a little collection of yours?” he asked. “The birds' eggs? The sea shells, perhaps?”
    “I'm afraid it's much more prosaic, Monsieur Poirot,” replied Barbara, with a nervous laugh. “Nothing but pills and powders!”
    “But surely,” said Poirot, “one so young, so full of health and vigour, has no need of these bagatelles?”
    “Oh, it's not for me,” Barbara assured him. “It's for Lucia. She's got such an awful headache this morning.”
    “La pauvre dame,” murmured Poirot, his voice dripping with sympathy. “She sent you for these pills, then?”
    “Yes,” replied Barbara. “I gave her a couple of aspirin, but she wanted some real dope. I said I'd bring up the whole outfit - that is, if no one were here.”
    Poirot, leaning his hands on the box, spoke thoughtfully.
    “If no one were here. Why would that matter, mademoiselle?”
    “Well, you know what it is in a place like this,” Barbara explained. “Fuss, fuss, fuss! I mean, Aunt Caroline, for instance, is like a ducky old hen! And Richard's a damned nuisance and completely useless into the bargain, as men always are when you're ill.”
    Poirot nodded in comprehension. “I understand, I understand,” he told Barbara, bowing his head as a sign that he accepted her explanation. He rubbed his fingers along the lid of the case containing the drugs, and then looked quickly at his hands. Pausing for a moment, he cleared his throat with a slightly affected sound, and then went on, “Do you know, mademoiselle, that you are very fortunate in your domestic servants?”
    “What do you mean?” asked Barbara.
    Poirot showed her the tin case.
    “See -” he pointed out, “on this box there is no speck of dust. To mount on a chair and bother to dust so high up