In the Bible exodus story the Children of Israel had been slaves in Egypt for four hundred years.  Then God appointed Moses as the deliverer who would approach Pharaoh the king of Egypt and demand he free the enslaved nation.  Pharaoh refused, and in response God brought ten plagues on Egypt which decimated the country.  First, their rivers and streams turned to blood.  Then the Egyptians were successively plagued with frogs, gnats, flies, livestock disease, boils, destructive hail storms, locusts, thick darkness, and finally all their firstborn sons were struck dead.  Pharaoh constantly changed his mind while his country was being ruined, but following the tenth plague he relented and let the Israelites leave.  This is a famous story which unsurprisingly has been depicted in many movies for it would be difficult to find a more dramatic tale. However, the exodus experience has lessons to teach us.  The Children of Israel had been stuck in a situation for a long time that they could not control.  They desperately wanted deliverance.  God heard their prayers and granted their petition.