Sue Mishler

Sue Mishler, codenamed "Ivan", was a special agent with the Federal Bureau of Investigation working undercover with Sergei Petrenko's criminal organization. Mishler spent four months as the chemist for their methamphetamine outfit based outside Topanga, California, and found herself the object of Petrenko's unwanted advances.

Mishler was present at the meth lab when Jack Bauer, undercover as local drug dealer Felix Studhalter, arrived with Petrenko, Malenkiy, and Franko to receive the latest shipment. As Petrenko greeted her, Franko whispered to Jack that she was the group's "combination scientist and cock tease." Before the deal was concluded, Petrenko received a call on his satellite phone from the real Felix Studhalter, blowing Jack's cover. Malenkiy and another man overpowered Jack, and Petrenko, ignoring his pleas that he didn't intend to bust them, ordered them to take him behind the cabin and kill him. Before they could, Mishler shot Malenkiy with a taser before kicking his partner over the edge. After both were dealt with, Mishler identified herself as Ivan, and furiously told Jack that he had ruined the last four months of her work. Both of them ran back to the cabin, and Jack hot-wired a BMW so they could pursue Petrenko and Franko.

As Mishler continued to berate Jack, they caught up with the meth truck and Petrenko's Mercedes in a dangerous chase down Topanga Canyon. As Petrenko fired on the car, Mishler returned fire with her Glock .40, eventually forcing the car off the road. Further down, the two switched places so that Jack could jump from the car into the back of the pickup truck. After Jack killed Franko and gained control of the vehicle, Mishler sped up and tried to block him in, so that he couldn't get away with the meth shipment. Admiring her tenacity but needing to get the drugs to Smiley Lopez, Jack sped up and rammed the BMW into the side of the mountain. Mishler was knocked unconscious but not seriously injured in the crash.