The Gorilla in the Vents (Royce Ree #3)
Aldous Mercer

MEANWHILE...
Royce has three days to rescue 40,000 space marines, thwart a homicidal Warlord, and save his ex's life. And he's just been told that the technology he came to Baldessh for doesn't actually exist, which means Royce is going to fail his mission, lose his job, and probably end up cleaning toilets in a dive-bar on Baga-V. But, sometimes, hope can be found in the darkest of places...like ventilation ducts.
“Every pre-FTL civilization we know of has alcohol. I mean, imagine being stuck to a single planet, wasting decades just crossing your own solar system! Who wouldn't invent vodka?
-Gaste Trade Cartel Sales Representative (Conversation overheard at spaceport dive-bar, Gomo-Prime)