Roman `Tsitadel` raskazyvaet o novykh prikljuchenijakh rytsarej - khramovnikov: o chestnykh poedinkakh i krovavykh bitvakh mezhdu krestonostsami i saratsinami, o zhestokikh assasinakh i kovarnykh ioannitakh, o tom, kak byl poterjan khristianami Ierusalim i kak zaschischali ego tampliery.