Riddle 029: Where is the Father?

[questionauthority]

{First, a public phone call, filtered from drones.]

Hello again, Mayfield. I've been noticing plenty of new faces around town as of late. Plenty of people with plenty of questions.

Every question has an answer, friends---I can guarantee you that. And I, Edward Nigma, can help you find all of these answers. And more. Now, I'm sure I can already predict the next question that's on your minds right now. "What's the catch?" Answer: I I'll be needing your help with a little summer project of mine. Here's your first clue as to what it might be.

“I cannot be seen and I weigh nothing,
But when put into a barrel, I make it lighter.”

What am I?

[It's just after finishing up with this little phone call that he gets his first good look at the calendar. Father's Day. Not exactly Edward's favorite day by any means, given his own relationship with his old man. Needless to say, his mood's been a little bit soured.

Throughout the rest of this lovely day, you're likely to run into the Riddler...

A: In the Backyard of 726 Anderson, sketching something out into a notebook.

B: Out for a drive in the Riddler-Mobile, to try and relax.

C: At Jonathan's Tools, loading up plenty of tools and building supplies into the back of his car.

Wherever he goes, he'll likely be sulking. Cheer him up? Help him out? He's all yours, ladies.]

Comments

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[autocrossbowplz.livejournal.com]

But you still need a physical base, if I understand correctly.

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[puzzlerprince.livejournal.com]

Exactly. Thus far, we've been able to hold two successful meetings at two separate locations. While we've been able to convene with little difficulty in either of these locations, the opportunity to build something a bit more permanent is growing all the more appealing.

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[autocrossbowplz.livejournal.com]

Hm... unfortunately, it seems unlikely that we'll be able to replicate the exact means I used to keep a permanent yet hidden base of operations, but perhaps we could borrow inspiration from it.

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[puzzlerprince.livejournal.com]

Oh? Please, do explain.

[Action]

[autocrossbowplz.livejournal.com]

My castle. Back home, I had a castle capable of diving beneath and tunneling through the deserts of Figaro - large, featureless deserts. Finding one's bearing was difficult, and made only more difficult when the destination moved.

Doesn't quite seem practical for Mayfield, however. There's too much architecture, it would be noticed if it tried to move anywhere. If we could manage something else equally mobile, though? Barring that, we could take it underground, but you would have to find a location where there are none droned.