Variation on an earlier idea:

After the most recent fun with thieves disguised as terrorists (which could be any of the movies! :D), John McClane gets a new partner. He keeps getting stuck with the undesirables because nobody else can handle his crazy, so it's not really a surprise that he gets stuck with the new guy...who just moved to New York from the UK. How much of the city will be destroyed in the name of saving lives before John McClane and Harry Potter get split up?