The Baroness seduced Sheik Mommar al Rhazidh and was invited back to his home. Once there, she drugged him, evaded his security personnel, and stole a map that led M.A.R.S. to a hidden cache of gold.

Ana DeCobray (née Lewis), a.k.a, Baroness was a member of Cobra. Baroness was extremely intelligent and skilled in hand to hand combat, melee weapons as well as all ranged fire arms. In addition to her tight leather suit, her equipment includes high-tech glasses and carrying pulse weapons.

She was secretly working with Storm Shadow to steal a new piece of M.A.R.S. designed weaponry from the U.S. Army and later the Joes. It was later revealed that the scientist referred to only as The Doctor used her grief and a nanotechnology form of mind control he had been developing to turn Ana into the Baroness. It was never revealed whether Ana's fighting prowess and high skill with many weapons was something she already had to any extent before the transformation, although it was revealed that she was tutored in ninjutsu and other martial arts by Storm Shadow, who considered her his best student. If Ana Lewis had any athletic abilities at the time she was engaged to Duke, it was not shown.

She was once the blond haired fiancée of Duke four years prior to the events of the film. Her one condition of the engagement was that Duke watch over her brother Rex and promise nothing bad will happen to him during their upcoming tour of duty. However, Rex was presumably killed in battle after Duke sends him into a building to retrieve valuable intel and an air strike he ordered bombs the building too early. Duke, feeling too much guilt, could not face Ana and left her.

Unknown to her, Rex was alive and he injected her with nanomites to alter her behavior and make her join Cobra. She got trained by Storm Shadow to become a highly skilled operative.

Four years later she was married to The Baron Daniel DeCobray, a scientist with a lab in Paris, France that Cobra wishes to use in their plans for world domination.

When failing to capture the Nanomite warheads from Duke and his unit because of the intervention of the Joes, she was scolded for her failure. Together with Zartan and her mentor Storm Shadow she invaded The Pit. During the fight she encountered Scarlett but managed to defeat her and knock her out. Escaping the scene she and Storm Shadown then planned to destroy Paris with one of the Nanomite warheads. As they blew up the Eiffel Tower, Duke stopped the nanobots, however she and Storm Shadow captured him. Ana refused Duke's apology for not saving her brother and revealed to him that Storm Shadow was mistrusted by the Arashikage Clan about his master's death. When Duke was threatened with mind control and beaten, Ana managed to fight off the control and begins having memory flashes of the love she shared with Duke. She managed to save Duke from the Doctor's experimentation after which he managed to save her after the Doctor threatened to kill her via her implants if he tried to kill either him or Destro.

Together, the Baroness and Duke managed to take down Cobra. Ana is then seen being examined by a doctor who says it will take time but he will be able to remove the nanomites. Duke informs her that until then, she will be kept in the brig of the USS Flagg, aircraft carrier of the Joes, and that they will see each other often. At least until Duke's tragic death in the sequel G.I. Joe: Retaliation. It's possible that she heard of his death.

It is possible that Ana will return in the canceled G.I Joe 3 to help the Joes and kill Cobra Commander to avenge Duke's death.