"Professional Courtesy" is a Starfinder adventure for four 5th-level characters. This adventure continues the Fly Free or Die Adventure Path, a six-part monthly campaign in which players take on the role of a merchant crew with an experimental starship, trying to get rich, escape interplanetary assassins, and outwit their rivals. This volume also details the aquatic world of Entha and its many dangerous and intelligent inhabitants, a well-armed Company warship, gear and character options for underwater adventures, and a series of "Side Jobs"—short mini-adventures the GM can insert into the campaign at any time.