As Enola searches for the missing Lady Blanchefleur del Campo, she discovers that her brother Sherlock is just as diligently searching for Enola herself, and this time he really needs to catch her! He is in possession of a most peculiar package, a message from their long-lost mother that only Enola can decipher. Sherlock, along with their brother Mycroft, must follow Enola into the reeking tunnels of London's dark underbelly as they solve a triple mystery: What has happened to their mother? And to Lady Blanchefleur? And what does either have to do with Mycroft, who holds Enola's future in his ever-so-proper hands? No one, not even Sherlock, is left unchanged or unsurprised in this brilliant conclusion to the Enola Holmes mystery series.