The ARTEMIS Team is an agency working for the President of the United States.
Okay, 'agency' is a major misnomer as this is a very, very small collection of people but they do in fact work for America's Chief Executive, With an interesting proviso: as he tells one of the key players in that group, "I don't want any current or advance notice of what you are doing, and as far as I am concerned, you do not exist. I have never heard of you."
That leader, President Laval, obviously wants plausible deniability but he definitely needs the team because of the proof they uncover of a major plan to unseat him and destroy democracy as the country has known it. And the powerful group behind the plot, I.O.A.G.I., is made up of a good number of very powerful and mega-rich people with their tentacles deep inside all the various governmental organizations in both the US and the UK - so much so that Laval admits he cannot ask for help from "the FBI, CIA, MI5 and 6" because "The simple answer to that question is that we don't know whom we can trust".
As the leader of ARTEMIS tells the President, "we have no way of knowing whom we can trust and who may be involved with [the other side]. We know that you are beyond reproach because they were trying to bring you down. The people around this table have all proven themselves to be reliable and free from the taint of that organization. We intend to carry out our mission for you, but we will not report to anyone, including you. Autonomy is vital to prevent any leakage or harm."
They named their group ARTEMIS after the mythological goddess of the hunt because their whole reason for existence is the hunt for, and dismantling of "a secret organization called I.O.A.G.I., which stands for the International Organization against Government Intervention. There are many influential people in this group from many countries in the West and East. Their raison d'etre is to make money and hold on to their power". That is a simple way of saying that the members are super wealthy and determined to keep what they have and make a whole lot more by destroying any government that looks like ti might be in their way.
The genesis of the group and their fight against that shadowy group started when Freya Jameson, wife of a presidential candidate named Charles learned that her husband was in deep with the group but had balked at their methods for unseating the current leader. Apparently qualms were forbidden and he was violently removed from the running (along with the women he was having an affair with). When Freya received an anonymous tip that there was a whole lot more to the murders than just a jealous husband learning of the tryst, she started to look into it.
Known for being a very intelligent woman, complete with a Ph.D., key players in I.O.A.G.I. went after her but underestimated her skills, tenacity, and luck. In doing so, they forced her to make use of total strangers which then put them in danger and gave them reason to join her fight.
The ARTEMIS Team is comprised of eight individuals"
Jack - Detective Chief Inspector until the 'official' formation of the team, he is the group leader and a highly skilled investigator who did not appreciate being used unknowingly by the enemy to put Freya behind bars to silence her - that and he quickly gained a major affection for the beautiful woman.
Freya - unofficial co-leader of the group, she brings to the group her expertise in economics coupled with her extensive contacts in the political area.
Deidre - a slim black woman in her thirties who "brings to the team her people skills and a good working knowledge of police procedure".
Alexander - an overweight white American male in his sixties, "an expert on anything mechanical".
Brady - a white American male in his probably late 30s and in very good shape providing the team "inside knowledge of the workings of the US security services".
Hassan - an Arab man who was a professor of mathematics in Tunis speaking several languages. He helped Freya when she desperately needed it.
Yvette - a slender French woman and until recently a prostitute who "has a talent for getting information from people".
Jeremiah - a teenage white American male, blond with freckles and sporting thick glasses, who is a nephew of Freya and a computer whiz recently released from jail for hacking the Pentagon.