So what happened to his son?

disappearance of his son

He was pretty clearly abducted, I thought. After that, nothing good happened. How many details do you need?

The plot doesn't hinge on this. Anderton's arc involves trying to move past this horrible event and the fallout from that, but the story doesn't require details of the son's disappearance, nor does it require a thoroughly detailed conclusion. It is enough to know that the son is forever gone.

Raped to death by Lamar

With all the future tech and philosophy in this movie, I thought the missing son was the most fascinating part. It's every parent's worse nightmare - you look away for a second and your child is gone and you never find out why. I think it's worse than your child dying - at least there can be closure there. The NOT knowing can ruin you. Look at John - It destroyed his marriage and got him hooked on drugs.

That scene where Agatha is describing Sean's future is so heartbreaking watching the parents' emotions run amok.