“What happened next is mere guesswork on my part, but I should say that Mrs. Inglethorp picked up the broken cup and placed it on the table by the bed. Feeling in need of a stimulant of some kind, she heated up her cocoa, and drank it off then and there. Now we are faced with a new problem. We know the cocoa contained no strychnine. The coffee was never drunk. Yet the strychnine must have been administered between seven and nine o’clock that evening. What third medium was there⁠—a medium so suitable for disguising the taste of strychnine that it is extraordinary no one has thought of it?” Poirot looked round the room, and then answered himself impressively. “Her medicine!”

“Do you mean that the murderer introduced the strychnine into her tonic?” I cried.