A goofily creepy cover by Neal Adams, I love the commercial guts it took to have The Phantom Stranger on it in this fashion. You didn't see a lot of Superman or Batman covers like this.
Inside, the story starts this way:
After the professor's body is found, an emergency meeting of the project's international scientists is called, and the stern Prof. Heinrich declares himself in charge. The rest of the board decides to wait until after the funeral to pick a new leader.
After the funeral (which the Stranger attends), another meeting is held, and Heinrich is passed over, in favor of someone else. He threatens to show them why he should be in charge. Uh-oh...
A week later, the same kid--Freddy--does the whole "bang bang" thing with the new project's leader, ending with the same result:
(...Prof. Henrich later got a job on Fox News)
The remaining scientists sedate Heinrich, since he keeps babbling about a mysteriously cloaked Stranger haunting him.
Later, Freddy does his thing with Dr. Clair, who, for once, doesn't fall over dead. We're making progress!
Another professor--Freddy's father--is put in charge, and, late at night, Freddy appears again, but luckily for Dr. Forsythe, the Stranger is there to intervene!
The Stranger says he is Phillip Strong, a professor's assistant here to help out the project. Forsythe buys this, and calms Freddy down and puts him back to bed.
Later, Forsythe is alone, holding Freddy's toy gun. He starts to think...
He then heads outside, where he sees Freddy running into the rocky cliffs outside. He confronts Freddy:
When their underground lair is threatened by atomic testing, the group who had this killer ability were sent out to the surface world, to infiltrate every atomic bomb project, with the goal of killing everyone in charge of it!
Why, sure, that makes total sen....what?!?
As if that wasn't enough, we find out that the kid-friendly Dr. Clair is actually Tala, who learned of this plot and wanted to help it along! The Stranger doesn't have any time for Tala's nonsense, and he chases after "Freddy":
I mean, you've got this super-secret atomic project, the mysterious deaths, the angry Dr. Heinrich (who is a red herring), The Phantom Stranger, a kid with mysterious powers, a whole alternate race of homo sapiens, Tala, plus a little social message. Whew!
There is another Dr. Thirteen solo story, "The Devil's Timepiece", by Kanigher and Tony De Zuniga, but I bet most people were too exhausted from the main story to even to read it. I know I was.