"It's the grumpy old kingdom-wizard's 211th birthday. Normally this would be no big deal (as no one likes him), but this generation of young royals will change all that by throwing him a special surprise party. However, when the birthday boy discovers their plot, things take a turn for the explosive, in this fantasy-comedy suitable for all readers."
All information about the book can be found here. And a link to the the shop is here (printed book is $10, digital copy is $4).