Rebecca Ross - Ruthless Vows (Letters of Enchantment Series, Book 2)

The epic conclusion to the intensely romantic and beautifully written story that started in Divine Rivals. Two weeks have passed since Iris returned home bruised and heartbroken from the front, but the war is far from over. Roman is missing, lost behind enemy lines, with no memory of his past, or Iris. Hoping his memories return, he begins to write again – but this time for the enemy. When a strange letter arrives through his wardrobe door, he strikes up a correspondence with a penpal who seems at once mysterious… and strangely familiar. As their connection deepens, the two of them will risk their very hearts and futures to change the tides of the war.