Richard Lester's The Three Musketeers

The first film features the arrival of D'Artagnan in Paris and his efforts to become a King's Musketeer, just like his father before him. In Paris he encounters three men who quickly become his friends and allies. Together they get entangled in court intrigues, and take up arms against the plotting, conniving Cardinal Richelieu. In the course of duty, they travel to England, where they try to preempt a scandal involving some diamond studs, the Duke of Buckingham and the reputation of the Queen of France. (official distributor synopsis)