The spy has set out to expose Sampath Chawla as a complete charlatan, the kind that he believes holds back the Indian people from becoming truly enlightened. An intellectual with a firm commitment to using reason to drive out superstition in all its forms, the spy is a man with a mission, a man committed to ridding India of self-declared holy men like Sampath.
All very admirable, one might think. And there's certainly no doubt that Sampath is indeed a charlatan. This is a man practically crying out to be exposed as a fraud. The problem, however, is that the spy is so full of his own importance that it's difficult to have much sympathy with him, even though we can still sympathize with his noble cause.
The spy's complete lack of self-awareness provides much of the humor in the story. Though only a humble teacher from the provinces, the spy acts like he's James Bond as he goes about his business sniffing around for the merest hint of fraud.
This huge gap between the spy's elevated self-perception and what he's actually like is very humorous, and Desai exploits it for all it's worth. This man, who hates his job, is disrespected by his pupils, leads a sad, empty life, and entertains fantasies of his becoming a public intellectual on TV.
But there's no chance whatsoever of his ever achieving such an exalted position in life. In holding on to such ludicrous fantasies, the spy is committing fraud on himself, somewhat ironic when you consider that his role as an investigator consists of rooting out fraud.