A blue green jewel, Beta Delphini II, home of the turtle like Chelonians. The world is old, and bears many scars, the craters from orbital bombardment and high power explosions, rings of dust and debris that were once starships, habitats, and fighter craft. But the world below remains tranquil, its wounds covered with blue seas and green forests.
The player characters, experienced and somewhat well known, hear rumors and travelers' tales about a distant area being overrun by dragons (or other terrifying monstrosities). The locals have sent them a message, begging for heroic aid.
When they investigate, they discover that nothing of the sort is going on. It turns out that a group of thieves wanted them out of the way so that they could rob them (or someone who would normally receive their protection).