That one was the boy, Harry Feversham.
He sat with his hands now clenched upon his knees and leaning forward a little across the table toward the surgeon, his cheeks white as paper, his eyes burning, and burning with ferocity.

He had the look of a dangerous animal in the trap.

His body was gathered, his muscles taut.
Sutch had a fear that the lad meant to leap across the table and strike with all his strength in the savagery of despair.

He had indeed reached out a restraining hand when General Feversham's matter-of-fact voice intervened, and the boy's attitude suddenly relaxed.
"Queer incomprehensible things happen.

Here are two of them.