There were two ways I was going to approach that story. They’re kind of mutually exclusive.
1) Rear Window style mystery where the invalid realizes that his neighbor is keeping a boy prisoner as a sex slave. The invalid has to combat his growing arousal at watching their interactions vs morality
2) The invalid witnesses the boy across the way committing a crime and proceeds to blackmail him into escalating exhibitions (bonus points if the boy still lives at home with his folks)