Existing parton shower Monte Carlos have been tremendously important in particle physics, both experimentally and theoretically. QCD coherence has allowed them to include the most important quantum mechanical interference effects within the framework of a classical parton branching algorithm. To improve their precision requires to go beyond the leading colour approximation, which necessarily means evolving at amplitude level so as to properly encode quantum mechanical interference. I will talk about our latest efforts to achieve this goal and some of the interesting QCD that one meets on the way.