I believe "the suspenseful moment" that the question is referring to is meant to indicate the time that Ravi spends hiding from Raghu in the shed. You are correct; it is a very suspenseful sequence. Lots of writers include suspenseful moments. Oftentimes, those moments are life-threatening experiences for the characters. Desai's story does not use that kind of suspense. Ravi is not in a life-threatening or dangerous situation, yet the hiding scene is very suspenseful, and it really draws readers into the conflict.
The reader is held in suspense and is very interested in the conflict because the conflict is so familiar to readers. We've all been kids before. We've all played hide-and-seek. We all know what the desire to win feels like. Desai has provided readers with a situation that we are intimately familiar with. When I play hide-and-seek with my own little kids, I can see the suspense on their faces when I come looking for them (and conveniently don't see them). Seeing my kids makes me remember those feelings from when I was a kid. Desai's story does that too. Readers practically read that section of the story while holding their breath, because we don't want to signal Raghu any more than Ravi does.
From there, Desai continues to build the suspense by describing the dark, spooky hiding place that Ravi has chosen. It's dark, unfamiliar, and loaded with creepy organisms.
But the shed smelled of rats, anthills, dust, and spider webs.
Most people have experienced being in a place like that before, and most people don't like the feeling. So again, the story keeps the interest of readers by continuing to be familiar.