"Merivel" (Robert Downey Jnr.) is an aspiring doctor who just happens to be in the right place at the right time. Charles II (Sam Neill) has just been restored to Britain's post-Cromwellian thrones and is rather fond of his spaniel. It's poorly, the doctor makes it better and next thing he's enjoying the life of a libertine at the king's court. Now the king has a reputation as a bit of a Lothario, so he decides to get his favourite physician to marry one of his mistresses so as to turn the heat down a little. The only stipulation is that he isn't to fall in love with "Celia" (Polly Walker)…