A guilt-ridden ex-detective investigates a missing person case tied to a child abduction he failed to solve years earlier, and which may be connected to a doomsday prophecy.

It feels like you tacked on "and which may be connected to a doomsday prophecy" in an effort to take your concept to an extreme and make it marketable, but the real issue is that you don't yet know what happens in Act II and III - or if you do, it's not showing up in your logline. You have an Act I: Detective emerges from retirement prompted by guilt over an unsolved case. But really all you have, for now, is "Detective emerges from retirement prompted by guilt over an unsolved case...and gets more than he bargained for." You need to focus on the "and gets more than he bargained for" because right now we can only "see" the first act, and we need to see all three.