Although Sydney re-welcomed Hicks and had a fling with him, several of the SD-6 employees (especially Dixon) believed he was a traitor.
After Noah and Sydney went on an infiltration mission together (which almost failed after Sydney nearly set off the alarms), they met each other on a beach.
Noah seemingly convinced Sydney to spend a week with him in the South Pacific to figure out if they could start a new life together. Sydney took the plane ticket he had purchased for her. Noah then called Sydney from his plane and she told him that she could not go with him because of her search for her mother. He said he understood and they said their goodbyes.
When Sydney was sent on a mission to Australia in order to find a VIP under the alias of Calder, she realized that both Calder and all of his guards had been murdered by an assassin. Sydney fought the assassin briefly. After he hesitated to kill her, the assassin rolled onto a knife used in the fight. When Sydney took off the assassin's mask, she discovered it was Noah - he was a double agent for K-Directorate all along. Noah said a hoarse goodbye to Sydney as she watched him die with tears in her eyes.