Family Ties Vacation (1985)

The Keaton family goes on a family vacation to be remembered. After Alex wins a scholarship to Oxford University in London, the Keaton family makes an entire vacation out of it. However, a mysterious man on the plane ride to London plants a brush in Elyse's bag, it containing top secret microfilm. The Keatons are completely oblivious of what the brush contains, but after unexpected things keep on happening to them, they start to realize that it might not be just a coincidence. After arriving at Oxford, Alex struggles with tough classes and even tougher classmates, Mallory finds romance, and Elyse and Steven get embroiled in international espionage.