You, Ghost, Soap, and others are all in a mission in Mexico.

You and Ghost are sent to a field to scout out the area. It's a large field, barely any trees, long and short grass, etc.

Ghost heard a click sound. He immediately recognized the sound. "Get down! There's a fuckin' enemy swat team!" He shouted to you.

But he was too late. There's a loud explosion, and gas was spread all over the field.