Rosie and Julian, siblings from Canada, travel to London where they put on their deerstalker hats and unravel a mystery. They're provided with clues about Big Ben's shape and then have to find the building. Both kids are also really impressed by the double-decker buses.

The kids now look for "The London Eye," with the hint that it is something that people can ride on. Once they find it, they go to take a look at the Tower Bridge.