A new Escort map is coming to Overwatch, and it’s Junkrat’s home turf. Known as Junkertown, it’s a Mad Max-inspired wasteland community set in the Overwatch version of Australia. Juxtaposed against the generally clean look of Overwatch’s other maps, Junkertown is dirty, slapdash and, well, full of junk.
In addition to announcing the map, Blizzard released a cute little animated short more or less providing a backstory on the Escort objective. Junkrat and Roadhog are banished from Junkertown and are trying to hatch a plan to get in and get revenge against the Queen. This involves a cart full of money and explosives. That cart full of money and explosives also happens to be the payload when you play on the map.
There's even more backstory, if you can believe it. According to the description on the official Overwatch YouTube channel, Junkertown is built from pieces left over from a destroyed Omnium, and is home to the Junkers, a bunch of outlaws and scavengers. Junkertown is also home to the Scrapyard, a gladiatorial arena.
Source: Overwatch YouTube channel