This chapter covers the end of the game. There are two possible outcomes depending on if you didn't give in during Ocelot's torture sequence in Chapter 4. If you did not give in, Meryl will be alive and you leave with her. She gives you the unlimited ammo head band which you have if you play through the game again. If you did give in, Meryl will be dead and Otacon will arrive. He gives you the Optic Camouflage for your next run through.
The escape sequence is exactly the same only Otacon is driving.