In a bid to search for her missing brother in Nepal, a Cambodian socialite poses as a doctor in a local earthquake relief mission. And as the location of his last known location draws closer, she comes to learns the preciousness of human relationships but must also come to terms with the possibility of her brother’s death.

This is too long. A logline should be under 40 words max.

“poses as a doctor” – how? Surely these kind of things are pretty heavily monitored and it’s not gonna take long before she’s found out. Also, your protagonist is someone who will knowingly put others at risk in order to find her brother. Why does she need to be in disguise?

“comes to learn the preciousness of human relationships” – what does this look like on screen? If she’s there to find her brother, it would suggest that she already understands how special some relationships are.

“come to terms with the possibility of her brother’s death” – again, what does this look like on screen?

A lot of what you have described here is happening inside the character’s head. A logline doesn’t need to concern itself with that. It simply needs to suggest an arc. I think the basic idea though, a sheltered socialite searching for her missing brother after a natural disaster, is great!

When her brother is missing after an earthquake in Nepal, a sheltered, narcissistic socialite travels to find him amidst the aftermath which devastated the country and its people.

It’s tricky with her character flaw because if you say she’s selfish, people will ask why is she trying to find her brother. I’m hoping that sheltered will suggest she hasn’t experienced much of the world and narcissistic will cover the attitude but still allow a little room for her to care about her brother. Sheltered alone might work just as well. It’s not perfect, admittedly.