The story tells the adventures of the wandering sailor Ishmael and his voyage on the whaling ship Pequod, commanded by Captain Ahab. Ishmael soon learns that Ahab does not mean to use the Pequod and her crew to hunt whales for market trade, as whaling ships generally do. Ahab seeks one specific whale, Moby-Dick, a white whale of tremendous size and ferocity. Comparatively few whaling ships know of Moby-Dick, and fewer yet have encountered him. In a previous encounter, the whale destroyed Ahab's boat and bit off his leg. Ahab intends to exact revenge.