“He met me head on, and we locked horns like a couple of moose. I had a death grip on his coat, and I felt it tearing. And then Bogard brought up his knee and planted it on me in a place I don’t like to talk about. I doubled over, sicker than seven hells. Tony Bogard picked up a bottle from the table in the middle of the room and christened me with it, as though I’d been a ship being launched. I went down and out.”
— Dan Turner in “Beyond Justice” by Robert Leslie Bellem.
As an aside (and sorry to digress), I wonder how PIs (and action heroes generally) get so many blows on the head but get away without any signs of subdural hematoma. Many times, they don’t even suffer either retrograde or anterograde amnesia.
Loss of consciousness (a concussion) always creates loss of memory for minutes to hours before the blow was struck and often also for some time after consciousness is regained. But our heroes always remember not only the moment before but often the blow itself! That doesn't happen in real life.
On the other end of the same process, both heroes and villains can produce instant, reliable, and safe coma using a single blow, easily and accurately, every time. Um...?
Nonetheless, private eyes seem to continue to be rendered unconscious with alarming frequency. Maybe they should start wearing a football helmet.