Eve was a hacker that Michael first met in season five "No Good Deed."
No Good Dead
THIS CONTAINS SPOILERS.
Barry's brother Paul came to Michael regarding the theft of a server containing the personal information and financial data of several thousand teachers. The team manages to trace the theft to a young and arrogant hacker named Eve.
Michael first approaches Eve in order to hire her to acquire a file for him (set up by Barry), with the intention of following her back to her hideout. However, she is clever enough to shake Fiona and Madeline off, and the team gives up on the idea of trailing her as a result. They eventually manage to find where she's staying, but not where she's hiding the stolen server; Jesse and Fiona attempt to search the hideout, but find nothing except shredded paperwork in the trash.
After she acquires the file, Michael hires her to decrypt it, with the stipulation that he has to be there personally for the file's decryption and the destruction of its copies. However, she sees through the fake escrow account Barry creates to hold the payment and drugs Michael by tricking him into pricking his fingers on a set of ketamine-laced needles. She brings him to a hidden location and tortures him for information (believing that Michael's assumed persona wasn't intelligent enough to set up something as complex as the fake escrow account), and he convinces her that he was hired by her other client as part of a double-cross (having learned her client's name from the paperwork taken from her trash). He convinces her that with the help of his crew, they can turn the tables on her employer.
Sam and Fiona show up at the address she gives them and assist her in capturing her employer and stealing the money he brought with him. She then disarms them and orders them to bind themselves after they load everything into her vehicle. She announces that she intends to renege on their deal and will execute everyone, at which point Fiona detonates the incendiary bomb she secretly attached to some of the equipment in Eve's Jeep, destroying both the money and the stolen computers. The shock knocks Eve over, giving Michael time to collect her gun and force her to surrender, and they bind her and leave her to the mercy of the Miami police department.
Presumed to be in jail since the events of No Good Deed.