He put his drink down in one piece and lunged for a mahogany call box on his desk. I caught the name Galbraith. I went over and unlocked the door.
I just wonder the meaning of above 'in one piece' is 'untouched or unharmed' as explained in dictionary, which mean he put down the glass on the desk without drinking.
Or aside from idiomatic dictionary meaning it is just a description of motion, that is, he put down his glass in an uninterrupted motion, regardless of drinking it or not.