This is a book I read in 4th grade, so about 2012-2013. This was in English and in the US.
This wasn't really a sci-fi novel that I remember, but definitely dystopian. It was set in the future of an African nation, I don't know which one. I don't remember any futuristic tech though...
There were 2 or 3 kids, I think maybe a girl and a boy or 2 boys and a girl. Their father was rich, they lived in a big nice house. Somehow they were kidnapped or ran away from somebody kidnapping them or something.
When the father + mother found they were gone, they sent 3 detectives after the kids.
The detectives traced the kids as the kids went through the slums, market, residential, across the whole city.
Eventually the kids were caught by some demon worship cult and going to be sacrificed, but the detectives rescued them.
Any ideas what this book is?