Clockwork princess

There is a time when a girl gets married. Aren't all girls happy when there wedding comes, but Tessa isn't. Tessa is a brave girl who is going to get married to James Carstairs , but Tessa has feelings for William Herondale too. The only problem she has besides the wedding is Mortmain, who is trying to destroy the shadowhunters . What is Tessa going to do if Mortmain has her????