Helena, Niamh, Leonie and Elle all once belonged to Her Royal Majesty's Coven - a coven of female witches who are a top-secret government agency designed to protect mundanes (humans). The girls are now in their 30's, and they are forced to come together once more when a prophecy of a Sullen Child heralds the end of days. With conflicting beliefs over the best course of action, the four friends must decide where their loyalties lie: with preserving tradition, or doing what is right.
This is so so good if you're also in a witchy phase like me and wanting an adult novel with darker magic. It's got possession, ancient prophecies and demonic frenemies. It's the start of a new series, and the ending is amazing - I CANNOT wait for the next book (I hope she's writing it as we speak). By the way, I do not recommend for under 16's - it is quite dark at times, and very adult (e.g. a lot of swearing).
— Brea