Nathan Fillion returns to our screens as Richard Castle this eve, and the writer turned crime-fighter is more than ready to get back into action with his on-again, off-again partner Kate Beckett. And no, we don't mean the kind of 'action' they were engaging in when we left them at the end of Season 4. Tonight the pair are hoping to solve a corruption case that has some very personal roots for Beckett. It just so happens that solving the whole thing may require a meeting with the man who killed her mammy...