Day 3: 11:00 P.M.-12:00 A.M. - S3-E11
Trivia: When the CTU personnel are in a meeting and Adam brings a picture of Nina onto the big screen, the name next to the picture is Sarah Berkeley, which is Sarah Clarke's married name. Clarke has been married to Xander Berkeley since 2002.
Day 3: 7:00 A.M.-8:00 A.M. - S3-E19
Trivia: The website for Sylvia Imports which David Palmer must use to provide Stephen Saunders with a list of the 42 overseas agents actually exists. On it is written: "Sylviaimports.com - A Big Thank-you from the crew of 24. Thanks for watching, we love making it for you, and yes, we did get picked up for Season 4."
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.
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