Class 3 of Hampstead Primary School are off on a school trip to Paris! Morgan is the first to spot the bearded man in the black Citroen car, cruising behind their school bus, and feels sure he is following them. The plot thickens when a second mysterious bearded man appears on the ferry boat, Soon Class 3 find themselves entangled with a group of art thieves intent upon stealing the Mona Lisa . . . !