Yes, he continued, staring at me thoughtfully, "you will be invaluable." This was naturally gratifying, but Poirot's next words were not so welcome. 
Poirot told me I would be invaluable to the investigation, but in the next breath seemed to disavow my usefulness.
mnli hypothesis: Poirot told me I would be invaluable to the investigation, but in the next breath seemed to disavow my usefulness. premise: Yes, he continued, staring at me thoughtfully, "you will be invaluable." This was naturally gratifying, but Poirot's next words were not so welcome. 