What is the first mission/level on Battlefield 3 ?

I want to know whats the first level on battlefield 3 can someone tell me and what is it about?|||Set in 2014,SSgt Blackburn leads a five-man squad on a mission to locate, find and safely return a US squad investigating a possible IED, whose last known position was a market controlled by a hostile militia called the PLR. Blackburn and his squad are later sent to Tehran to apprehend a the leader of the PLR, Al-Bashir. While investigating an underground vault in the target's suspected location, Blackburn and his team learn that the PLR acquired Russian portable nuclear devices, and that two of the three devices are missing. Being overrun, and requesting back-up, an M1 Abrams convoy led by Sergeant Miller is deployed to extract Blackburn's team. Miller facilitates Blackburn's helicopter extraction, but is captured when waiting for a Quick Reaction Force. Miller is promptly executed by Solomon and Al-Bashir, with the event being filmed.