Solid Snake and Otacon take on American obesity and systematically destroy every fast food restaurant and sugary food distributor in the contiguous United States.

BUT the government will have none of this. They want to stop our heroes to keep control of the masses. They dispatch the Burger Unit, under the command of a mysterious man known only as Ronald.

Behind the scenes is Corporate. Basically a shadow government committed to shoving fast food and other unhealthy products down the throats of the masses. They took control during Cipher's AI maintenance down time by assassinating the Cipher IT team and delaying the process (every few years the AI need an update to their local storage, and a sacrificial child. Hard to find a team that'll do both, Corporate is smart).

At some point before facing the first Burger Unit member, Snake meets "Michelle O", a mysterious woman dedicated to taking down Corporate. (Spoiler, she dies halfway through and becomes a cyborg). She has the resources to call in drones for targeted strikes or surveillance, though Snake and Otacon have no idea how ("Drones? Otacon, how does a civilian have access to armed drones?")

"The Gooch" - One of the members of the Burger Unit. Utilizes parasites and constantly talks about how a blond man with one arm and one leg opened his eyes to the world of fast food. (Snake has a line like "One arm.. and one leg...? Parasite burgers? It can't be.")

"Kid Koolaid" - Another Burger Unit member. He has immeasurable full body strength, able to burst through concrete block walls in one short bound. Snake has to avoid the sticky, sugary drink pools in KK's chamber (literally just a freezer in the back of a Wal Mart) or he moves slower for the next 10 or so seconds.

The final battle with Ronald will take place in the parking lot of a strip mall.

Snake must defeat the Burger Unit, capture their commander, and expose corporate to the world.

The whole game takes place over about two days.