The Four Musketeers (1974)

  Apparently this was filmed all at once with the previous Three Musketeers but released in two parts after the producers realized it was long enough for two films.  The actors were pissed when they found out about it and now there's a clause in every guild contract that says you can't do that anymore.  That's a pretty decent legacy for what would otherwise be a throwaway period comedy.

Not knowing all that until I was researching this, I was initially impressed that they managed to get such good continuity between movies. 

Milady du Winter (Faye Dunaway) is super-pissed after her scheme to ruin the Queen of France (Geraldine Chaplin) was foiled by D'Artagnan (Michael York) and his lady love Constance (Raquel Welch).  She and Count Rochefort (Christopher Lee) begin their revenge by kidnapping Constance while the musketeers are distracted by the siege of Protestant rebels at La Rochelle.  Our heroes manage to take La Rochelle and rescue Constance, depositing her in a convent, at roughly the same time.  Cardinal Richelieu (Charlton Heston) wants Milady to assassinate the Duke of Buckingham (Simon Ward) so he'll stop funding the heretics.  She agrees, in return for a signed warrant giving her carte blanche to kill D'Artagnan and his mistress.  Athos (Oliver Reed) overhears the plot and threatens to kill her if she proceeds.  She knows he'll do it, too, because they used to be married.  She just can't help herself, however, and a huge showdown ensues at the convent.

Every adaptation of this book is different, so much so that I can no longer remember what the book actually says.  This one ends with kind of a downer, which I actually preferred to the sappy comedy of the first one.  I think it would be interesting if they recut this to make it one long epic, they way it was initially intended, and see how well it would flow from beginning to end like that.