The Beanstalk Murder - a middle grade fantasy novel by P. G. Bell - involves a young witch in training, her archenemy, the kingdom of giants, and a huge murder mystery!
Anwen sedge, a young meadow witch apprentice, lives in a rural village that hasn’t seen giants since the Great Beanstalk War. So it’s quite a surprise when one drops from the sky and squishes the village flat. It’s an even bigger surprise when Anwen discovers that he was dead before he hit the ground. This is a murder! The only solution is for Anwen and her arch nemesis, Cerys (who’s the best at High Magic and won’t let anyone forget it), to send a plea for help to the giants’ kingdom, using a magic beanstalk.