Silver and Lead by Seanan McGuire (October Daye #19)
Something is rotten in Faerie. In the aftermath of Titania's reality-warping enchantment, things are returning to what passes for normal in the Kingdom in the Mists—until it's discovered that the royal vaults have been looted, and several powerful magical artifacts are missing. None are things that can be safely left unsecured, and some have the potential to do almost as much damage as Titania did, and having them in the wrong hands could prove just as disastrous. At least the theft means that Sir October "Toby" Daye, Knight errant and Hero of the Realm, finally has an excuse to get out of the house. Sure, she's eight and a half months pregnant, but that doesn't mean she can’t take care of herself. But with the sea witch offering to stand godmother to Toby's child, maybe there are greater dangers ahead for Toby and her family than it appears.... Old enemies will resurface, new enemies will disguise themselves as friends, and Queen Windermere must try to ke...
