The First Book of Lankhmar.

From the moment when they first met, in the commission of the same, audacious theft, Fafhrd, the giant barbarian warrior from the Cold Waste, and the Gray Mouser, master thief, novice wizard and expert swordsman, felt no ordinary affinity. Forged over the gleam of sharpened steel as, back to back, they faced their foes, theirs was a friendship that would take them from adventure to misadventure across all of Nehwon, from the caves of the inner earth to the waves of the outer sea. But it was in the dark alleys and noisome back streets of the great fog-shrouded city of Lankhmar that they became legends. The First Book of Lankhmar includes the first four volumes of the hugely enjoyable Swords series.