The Magician's Trunk (McCabe and Cody Book 13)

"Perhaps by this point you already know that I have willed you all my books on magic and my magician's trunk, a kind of relic which once belonged to the Great Blackstone-Harry Blackstone, Sr. You also get the contents of the trunk. Some of those contents you can keep, some you will know how to redirect appropriately."

So wrote the late Septimus Pogue to Sebastian McCabe, to whom he was a mentor in Mac's youth. The only problem is that the Blackstone trunk is missing...