When D’Artacan shows off his new dagger to Pom, he is robbed of it by Milady. His friends find out that she is one of Richelieu’s agents. Richelieu sends Milady to London to get hold of the Queen’s necklace, and then sets up events in Paris so that the Queen will be obliged to wear the missing necklace at a ball. D’Artacan and the Three Muskehounds are quickly dispatched to London.