Moses was chosen by God to free the Israelites from Egypt. Moses was sent to the king pharaoh to let Israelites go but their king refused. So Moses told him about the plagues that would befall them, but pharaoh was adamant until the death of every first son of Egypt happened. Finally he let them go but still chased after them to the Red sea, it was at the red sea Moses performed the miracle of splitting the sea with his rod and drowning the Egyptians in the process.
This book tells us about the encounter of the Israelites during their captivity in Egypt.