The Alchemist of Netley Abbey — Cassandra Clark

Desperate to return home to Meaux after the traumatic events in London and Salisbury, intrepid nun, Hildegard, and her charismatic but untouchable abbot, Hubert de Courcy, set out with their two monks militant through the New Forest on the long journey north at last.
Fate, however, intervenes.
Even before they escape the labyrinthine paths of the Royal Forest Hubert is in need of urgent medical attention and they are forced to seek shelter at the mysterious Netley Abbey. Although welcomed inside the precincts, all is not as it seems. A motley group of pilgrims are waiting to take ship to France. Guests secretly come and go. Who are they? Are they spies, assassins, or something even more threatening to the safety of King Richard's realm? And why are they here in this remote and beautiful place?
A Welsh alchemist reputed to have mysterious powers adds his own sinister desires to the brew and when a valuable book disappears and two deaths follow, who is to blame?
As usual Hildegard is entangled in a web of intrigue and defies all dangers to discover the truth.