Arnold and his friends must recover a stolen document in order to prevent the neighborhood from being bulldozed.

When their trip to San Lorenzo takes a turn for the worst, Arnold and his classmate’s only hope of getting home is retracing the dangerous path that led to Arnold's parents' disappearance.

When Arnold receives Mr. Hyunh's name in the boarding house's annual Secret Santa draw, he decides to make it the most special Christmas ever for the lonely boarder, and tries to reunite Mr. Hyunh with his long-lost daughter. Meanwhile, Helga agonizes over what would make the perfect present for Arnold.