Susan watches the angel quickly deal with the shadows, deciding it may be best to get a better gauge of her potential snacks real abilities before she makes her move. That mace looked like it would leave a nasty bruise. She goes to back up, when the floorboards give out, sending her, and the entire room she's in for that matter crashing down behind the angel, the impact just about shaking the whole house. Luckily, aside from  a few stray floorboards landing on her, she's dazed, but unhurt.