(NBC News) — On a new Thursday “Dateline,” when a United States Air Force airman is shot multiple times inside his garage, a trail of clues leads Las Vegas detectives to a secret love affair and a murderous plan.

Here is a preview of Keith Morrison’s report:

DETECTIVE TOD WILLIAMS: Every bad guy that’s ever lived has come through Vegas at one point in his career.

As a homicide detective for Las Vegas Metro PD In Nevada, Tod Williams saw it all.

TOD WILLIAMS: Whether you’re a plumber or a policeman, you wanna go where the work is. And there’s lots of good police work here in Las Vegas.

KEITH MORRISON: That’s certainly one way to look at it.

Williams did the work for 30 years, never once sharing his cases with the media.

DETECTIVE TOD WILLIAMS: I’ve always refused these.

KEITH MORRISON: How come?

DETECTIVE TOD WILLIAMS: I just didn’t feel like murder was entertainment or should be entertainment. That’s the best way I could describe it. So, I’ve got my reasons for doing this now.

Reasons that perhaps will make sense once you hear the whole story.

Which began — for Tod Williams — on a cold, December night in 2010 in a family home on a quiet street, 13 miles — and a world away — from the Las Vegas Strip.

CALLER: Oh my God, please.

911: What’s going on there?

Where horror had just come to call.

WIFE: My husband — he just walked in the garage. He’s bleeding.

911: I need you to calm down, just a little bit.

WIFE: Oh my God.

Watch “Dateline: Part of the Plan,” Thursday at 10 p.m. on NBC4.