Day 8: 1:00 P.M. - 2:00 P.M. - S8-E22
Continuity mistake: Day 8: 1:00 p.m.-2:00 p.m: When Chloe frees Cole from the detention cell she closes the door behind her. But once they're finished talking and they turn to leave the door is suddenly open again.
Answer: According to Jack in season 5, Nina was "deep cover" before the pair ever met, so it's safe to assume she was recruited before she joined CTU. As for what her primary mission was, who knows? Perhaps it was to gather sensitive intel and pass it on to her superiors. Given that she worked for an intelligence agency, it's not a stretch. Or perhaps we may find out in season seven.
Cubs Fan ★