City of Golden Shadow 

by Tad Williams

Otherland 
(Book 1)

Renie Sulaweyo, a teacher in the South Africa of tomorrow, realizes something is wrong on the network. Kids, including her brother Stephen, have logged into the net, and cannot escape. Clues point to a mysterious golden city called Otherland, but investigators all end up dead.

Goodreads: 3.93
3.93/5