Ainz and Narberal (one of the Battle Maids of Nazarick) take on the aliases of Momon and Nabe, respectively, in order to join the adventurer's guild in the city of E-Rantel to learn more about the world. Several complications arise when "Momon" finds it troublesome to keep "Nabe" from blowing their cover while rowdy adventurers try to win Nabe's attention (which only annoys her). Meanwhile, a dangerous necromancer and a bloodthirsty female assassin plot a takeover of E-Rantel.