A single prophet against four hundred. That was the lineup on Mount Carmel, and Elijah liked his odds.
The backstory is bleak. King Ahab had married Jezebel, daughter of Ethbaal, king of the Tyrians and Sidonians. She built a temple to Baal, planted sacred groves, appointed false prophets by the hundreds, and hunted down the prophets of God. So God sent Elijah with one devastating sentence: no rain, no dew, until the prophet says otherwise.
The drought was total. Rivers dried up. The land couldn't feed horses, let alone people. God kept Elijah alive through miracles: ravens brought him bread by a brook, and when that dried, a widow in Zarephath fed him from a jar of meal and cruse of oil that never ran out. When her son died, Elijah prayed until the child's soul returned.
Then came the showdown. Elijah gathered all Israel to Mount Carmel and put the question plainly: how long will you waver between two gods? Both sides would prepare a sacrifice but light no fire. Whichever god answered with flame was the true God. Baal's four hundred prophets went first. They prayed from morning to noon. Nothing. Elijah mocked them. They screamed louder, cut themselves with swords. Still nothing.
Elijah built an altar of twelve stones, one for each tribe. He drenched the sacrifice and wood with water, filling even the trench around it. Then he prayed once. Fire fell from heaven and consumed everything, the sacrifice, the wood, the stones, even the water. The people fell on their faces and declared the God of Israel alone was true. Elijah ordered Baal's prophets seized and killed, every one of them.
Then Elijah told Ahab to eat, because rain was coming. He climbed to Carmel's peak, put his head between his knees, and sent his servant to watch the horizon. Six times, nothing. On the seventh look, a cloud no bigger than a man's foot. The sky went black, the wind roared, rain poured down. And Elijah, seized by divine power, ran ahead of the king's chariot all the way to Jezreel.