Ariana Kane was on a witch hunt and targeted Jack Bristow. She believed that he had the perfect motive to blackmail Sloane. Ariana believed several of Jack's missions were suspicious and she heavily investigated them. This prompted Jack, with the help of the CIA, to create security footage and hard evidence, proving that he had indeed been in the locations stated by his missions. This evidence passed Ariana's scrutiny but she was not satisfied. Ariana requested Jack's SIM card to verify phone calls and cell-tower information. Agent Michael Vaughn attempted to help Jack but the attempt failed and Jack went into hiding at the CIA operations base.
Sydney Bristow's cover was nearly blown while having dinner with Vaughn. Ariana's agents identified Vaughn leaving the airport with Sydney and discovered that he worked for the CIA by hacking into the DMV database. Vaughn and Sydney neutralised the agents and Ariana never discovered Sydney's affiliation with the CIA.
Jack Bristow with the help of Irina Derevko discovered that Ariana was behind the blackmailing of the Alliance as bank records showed she had deposited the Bearer Bonds into an account only long enough to convert into cash.