He was not spying on the family, merely on his meddling brother officers.
Tony of course could know nothing of this, and as his eyes fell upon the lieutenant, there was apparent in their depths a large measure of contempt.

A lieutenant in the Royal Italian Cavalry can afford to be generous in many things, but he cannot afford to swallow contempt from a donkey-driver.

The signorina was not present this time; there was no reason why he should not punish the fellow.

He dropped his hand on Tony's shoulder--on his collar to be exact--and whirled him about.

The action was accompanied by some vigorous colloquial Italian--the gist of it being that Tony was to mind his own business and mend his manners.