Diane Duane answers the question in this volume, collecting together the three canonical works that constitute a "transitional trilogy" between books 9 and 10 -- a 150,000-word extravaganza of heretofore untold tales. Interim Errantry contains:

The novella Not On My Patch, the tale of an unusual Halloween in the Young Wizards' neighborhood, featuring overage Trick Or Treating, suburban zombies, and the Attack of the Killer Pumpkins.

The novelette How Lovely Are Thy Branches, a holiday-themed Young Wizards story in which an alien wizard who looks a lot like a Christmas tree gets the gift he wants most -- decorations -- and a memorable party and sleepover party are disrupted by a superblizzard and an incursion of alien ghosts.

And finally, the new original Young Wizards novel Lifeboats, the tale of a distant world threatened by unavoidable doom, an intervention that takes thousands of Earth's wizards, young and old, into harm's way, and a Valentine's Day that absolutely doesn't go as planned...

So settle down with a pumpkin spice latte (or a hot cocoa, or even just some tea and saltines...) and get ready to enjoy the highlights of autumn 2010 and winter 2011 in the Young Wizards universe!