Samantha 'Sam' Driver is an agent with a U.N. Unofficial Agency.
That designation takes some explaining.
When we first meet this very capable, and very very dangerous woman, she is an experienced CIA agent working a clandestine operation in Kazakhstan with a SEAL team to capture a very nasty, very wanted terrorist named Abbas Jemal, "keeper of all January Seven's [a terrorist group] dirty secrets". They had all been preparing for the snatch for two months and all looked fine. Then it wasn't. Someome had betrayed them or set them up and several good men died, including the lead Seal, Tom McNeil with whom Driver had been having a relationship. Driver held his dying body until the end and she became a prisoner sent to Siberia.
Jump ahead two years.
Some very bad people had recently attacked the American embassy in Moscow, killing several good people including the Ambassador. American anger at the Russians was extremely high. The feelings were mutual because of a previous attack on the Russian compound in Washington. Rhetoric was flowing and talk of war was rampant. It was a powderkeg both literally and figuratively.
At the U.N. several representatives to the Security Council came up with a plan. Since none of the intelligence agencies around the world had figured out who was really behind the attacks and none were willing to work with each other out of anger and distrust, these diplomats would put together their own team.
The idea was that this group would answer to no nation. More importantly, it would be "allowed" to do things that the official bureaus would not, simply because it was totally unofficial and therefore did not really exist.
To man this team, the group picked a half dozen operatives who had been captured by another country and then been disavowed by their own nation. An American held by the Russians. A Russian held by the French. An Australian held by the Chinese. A Chinese agent held by the English. A Mexican held by the Americans. Driver was the American in the group.
Each diplomat used his or her considerable pull in their native countries to get these people released and offered a contract to work for them. The deal was simple. Get the job done and you stay out of prison.
Nobody said anything about staying alive.