Conspiracy 365: December by Gabrielle Lord (December 2010, Hodder Children's Books, ISBN: 0340996552)
Notes: I've previously reviewed January, June, August and October and November
Review: December is the final part in the twelve-book series which began with January. It's a slightly longer book than its predecessors and is an exciting and worthy finale to the tale of Cal Ormond.
Cal has been on the run for twelve months. His task was to a) stay alive and b) solve the mystery of the Ormonds ie find the Ormond Singularity with the help of the Ormond Jewel and Ormond Riddle. The latter two objects have been in and out of his possession for most of the year but finally he has them, and with his two friends, Winter and Boges, they make good progress in solving the mystery.
Having been in Australia for the previous 11 months, the story ends in Ireland where it had begun with Cal's Dad before he became ill and died.
You could read December as a stand-alone but it would be more satisfying to have read some, or all of the earlier books. I was pleased with the resolution to the mysteries and surprised by many of the twists. December was a strong entry in a series which was a little uneven: some months were better than others with the story not moving on in some and a tendency towards some repetition; Cal does seems to have an unfeasibly large number of handy skills plus quite a bit of luck at times, nonetheless I'm glad I read all twelve.
Initially I felt sad that the series had ended as I would like to have read more about Cal and his friends but it seems I may have my wish as I discovered that a 13th book is on the way, called Revenge according to the Conspiracy 365 website.