Morgana takes the dying Morgause to the Isle of the Blessed where she unwittingly tears the veil to the spirit world, unleashing the Dorocha, invisible ghosts that begin to attack the kingdom. At Camelot, where a weakened Uther has given over much of his rule to his scheming brother Agravaine, Merlin senses what is happening but finds his magic inadequate to stop it. As Camelot fills with refugees, Gaius reasons that, as one death opened the portal, only another will close it. Arthur offers himself as the sacrifice and travels to the Isle of the Blessed with Merlin and a group of young knights. Here, after Arthur has finally praised him for his bravery, Merlin appears to have a fatal encounter with one of the Dorocha. 【S4FInale】今夜国王将失身。居然－－－表扬第四季第七集（剧透）。献给谦卑善良、温柔体贴的高贵骑士-小兰（S4E02剧透、慎入）。《梅林》第四季第一集吐槽（剧透哦）。"U know how many times I saved ur life?'''I know.''(S4E01剧透，慎入)。《梅林》S4第三集吐血剧评（严重剧透）。仁者无敌？－－《梅林》第四季第五集（剧透）。欲说还休，欲休又说之《梅林》第四季总评。看到11集了，我还是憋不住了。过渡---《梅林》第十集。 本剧根据亚瑟王与魔法师梅林的故事改编，由BBC威尔士电视台与Shine影视公司共同出品。 莫根娜夺权计划失败后，带领奄奄一息的莫高斯逃离了卡美洛，在萨温节之夜，莫根娜在莫高斯的要求下将她血祭，以便打破世界与灵界的隔膜，好创造出一个新的世界；灵界的守门人冬之灵告诉她，有一个名叫艾默瑞斯的人将会成为她的劫数，从此莫根娜便躲在了森林深处的一个黑屋里，并利用亚瑟的舅舅阿古温计划着打击卡美洛，并寻找艾默瑞斯的下落。亚瑟和他的骑士，还有男仆梅林（科林·摩根 Colin Morgan 饰）继续踏上寻觅神佑之岛的道路。而在途中梅林为保护亚瑟而被怨灵缠身,醒来的梅林召唤出了龙，并找到救补结界的方法。莫根娜的背叛使乌瑟极度消沉，不理朝政，最终在莫根娜的算计下不幸驾崩，后由亚瑟继承了王位……
