Aphrodite

"Uh, Hunk? Some help, please? There's gotta be a way to open this thing!"
[Muffled auditory signals, coming from above. Overheated, system failure.]
"Uh... I don't know, Pidge, I don't usually go around opening up strange, wrecked alien ships!"
"Oh, c'mon! Don't be such a baby and help me! Put those huge arms to use!"

The year is 5036.
Humans have long since settled into a comfortable, albeit somewhat unwanted, harmony with the powerful Alteans on the 10th and last floor.
Humanity is crammed between level 2 and 8, densely packed.
Floor 1 is just below the Earth's sufrace and has for thousands of years been dedicated to the shunned Garlas.
90% of the Earth's surface area is built upon, only one ocean remaining.

Then...

One day a strange, hidden visitor somehow manages to crash land on the second floor city-system Panthera.
Pidge and Hunk decide to awaken it.