Cartoonish as it may sound—as is the case with so many deadly-serious but still far-out military concepts—it makes a lot of sense. And Darpa, the Pentagon's weapon of choice for making crazy things happen, just chose four companies to push the idea forward.

Called Gremlins (because you weren't already freaked out) the project calls for a new type of reusable unmanned aerial vehicle that can be air-launched on intelligence-gathering missions from cargo airplanes, bombers, or other military aircraft over "denied" (i.e., hostile) airspace.

Once their missions are complete, up to three hours later, the drones will fly back to retrieval area where a C-130 cargo airplane will collect them. Darpa released a call for proposals in the fall, and just announced the four teams short-listed for further development: