A war veteran struck by a mysterious life-threatening illness.

His sugar had dropped in a matter of minutes that sent him into cardiac arrest.

He was non-diabetic, and there was absolutely no reason for his blood sugar to be low.

As investigators dig into the mystery,

a disturbing pattern comes to light.

There were events with a number of patients

of unexplained hypoglycemia.

The rumor mill spread around the hospital.

It could have been anybody.

It was pretty clear something terrible had gone wrong at this hospital.

All of the deaths in this case occurred in a single unit of the hospital.

To unearth the horrifying truth, investigators must expose a killer

preying on a community's most vulnerable members.

These events couldn't be occurring naturally or by accident.

This was being done by someone.

Insulin had been administered subcutaneously or injected into the patients.

Did you have anything to do with the deaths or incidents for these patients?

Absolutely known.

That's no angel of mercy to me. That's a monster. Clarksburg, West Virginia is a small town with a proud history.

It's home to the Lewis A. Johnson Medical Center,

which is one of the 172 veterans hospitals

distributed across the United States.

...