Ghostwriter

Little do Dime or Belfry know, when Belfry's belongings were confiscated one of the infiltrators had bugged the device to track where the message would be sent. Planets fit for life might be a bit more common in this universe, but still a rarity. But why wouldn't they simply use the device themselves? The beacon simply wouldn't recognize them. As a safety precaution, the beacon would only function for the species that built it.

And if the bug was removed or this otherwise didn't pan out, well. They would take a more active interest in the beacon. The Lizard people believe the boxes belong to them and aren't keen on the idea of some third party swiping even a few from their clawed grip.

SpoilerShow

Hm. Thinking about it earlier, we haven't named any of the planets yet.
I thought Chiron, Eucalyptis, Dachydis might work for placeholder names, but it had occurred to me that if they're going to be placeholder names might as well make them easy to remember.
So...
Boxworld/Boxlandia, Quarter, Refugia?
Placeholder names being placeholders, certainly open to alternatives.

While I'm at it, let me see if my notes are straight.
Three Two planets, two(?) three species, and our current characters of interest Belfry and Dime.

Although rereading it, I may have mistaken our current planet as separate from boxworld?
Hrm. Well, in that case it would be mysterious outsider sent lizard people to infiltrate boxworld
No, no. We started with boxworld, with its tripod citizens. One world, one species. Lizard aliens wanted boxworlds boxes, launched secret invasion. (to be followed by real invasion.) That would be two species. Now we get to Belfry Retting and Dime, with Belfry of a species originating on another world. So three species, two planets. I think that's about right for the time being.

Something strange would occur. Radio's would pick up an odd noise on an otherwise unused frequency. For ten minutes, it played the sound of a drum beating. Or perhaps, a heart. None would hear this at the time, or think much of it when it was found later.