I had bought the last of a favourite YA series, 'Fyre' by Angie Sage. Her Septimus Heap series is a wonderfully realised world, and 'Fyre' a fabulous concluding book. I read 'Fyre', then immediately went back and re read the series from the beginning;
45) Magyk
46) Flyte
47) Physik
48) Queste
49) Syren
50) Darke
51) Fyre
Through these 7 books you watch Septimus the seventh son of a seventh son, Jenna the Castle's Princess and Beetle a Castle Scribe grow into themselves and undertake adventures as they repeatedly secure the safety of the Castle and it's inhabitants from those who would cause harm. Original, inventive and stunningly well depicted, this series has been a delight.