Where is Moses when you need him ?
God reveals his plan to Moses: Exodus 4:21-23
The plagues: Exodus 7-11
Pharaoh decides to pursue the Israelites: Exodus 14:1-9
In particular, consider Exodus 9:34-10:2:
When Pharaoh saw that the rain and hail and thunder had stopped, he sinned again: He and his officials hardened their hearts. So Pharaoh's heart was hard and he would not let the Israelites go, just as the LORD had said through Moses.
Then the LORD said to Moses, "Go to Pharaoh, for I have hardened his heart and the hearts of his officials so that I may perform these miraculous signs of mine among them that you may tell your children and grandchildren how I dealt harshly with the Egyptians and how I performed my signs among them, and that you may know that I am the LORD."
God knew in advance what Pharaoh would do in any given situation, and deliberately placed Pharaoh in this situation (i.e. God decided that Pharaoh would be born at the time and place that he was and thus placed him in this position of power). (See Exodus 9:13-16.) Link
Thus God brought about the situation, namely that Moses would encounter a pharaoh whose heart was hardened against God and would be forced to defend the innocents from the mad Pharaoh, with the help of God, in such an remarkable way that the lesson is still with us, more than 2,000 years later...