'Twas the night before Christmas and all through the house, not a creature was stirring ... except for a platypus. When Dr. Doofenshmirtz creates an -inator that sabotages St. Nick, it's up to Agent P to save the day . . . and save it he does, reversing Doofenshmirtz's -inator and making it home just before Phineas and Ferb wake up on Christmas morning.