InvestiGators: Take the Plunge by John Patrick Green
From First Second Books:
Sewer-loving secret agents Mango and Brash are plunged into a new mystery—and a BIG mess—in John Patrick Green's hilarious adventure-packed graphic novel, InvestiGators: Take the Plunge.
S.U.I.T. headquarters is under attack, and Mango and Brash are going undercover and underground disguised as city sewer workers to unclog a sticky situation. But when their search for the criminal Crackerdile backfires, the toilets they travel through back up—and the InvestiGators take the blame for it!
Can Mango and Brash restore their good name and put the real culprit behind bars before the whole city is in deep water?