When did the professor exhibit his horrible heartiness What was its effect Chapter the man who knew too much?

In "The Man Who Knew Too Much," the professor exhibits his horrible heartiness during a dinner party, where his boisterous laughter and jovial demeanor starkly contrast the tension of the situation. This unsettling behavior serves to highlight his obliviousness to the danger around him, creating an atmosphere of unease among the guests. His heartiness ultimately underscores the theme of danger lurking beneath a facade of normalcy, as it distracts from the seriousness of the circumstances they face.