The show centres on Shirou Emiya a young sorcerer with very limited powers. One day however, Shirou accidentally gets involved in a dangerous situation and he summons a servant to save him. It turns out that Shirou has become involved in the Holy Grail War, a battle in which seven sorcerers each summon a servant (these servants are actually famous historical figures that must take on assumed names so that they do not expose their weaknesses to their enemy's for example Berserker is Hercules, Saber is Quinevere etc)and they fight to the death. When only one sorcerer remans they are granted the Holy Grail and thus may make any wish they dsire and have it come true.
This is an excellent anime with some very cool fight scenes and some excellent animation. The only downside is that the last few episodes feel very rushed and could have done with being padded out over an extra few epeisodes. Despite this it is still excellent.