There are these kids (middle school or high school?) in this boarding school or orphanage on a cliff or in the countryside. They've pretty much all got gray or white hair, as a side effect of the pills they have to take. It turns out that the kids are all orphaned or abandoned children, and the school is using them as test subjects. The pills they take are intelligence (?) enhancers of some sort. At some point, a pair of parents comes and picks up the child they abandoned and takes them away.

The Hour of the Mice?

Yes, that's it! thank you