Fate/Apocrypha is one of the bigger anime set for release in Summer 2017, but if you live outside of Japan, you would be better of considering it a Fall 2017 anime. The reason for that you ask? Netflix got the rights.
Before I go into full rant mode, let me just fill you in on some of the other details of this anime. Fate/Apocrypha is set in a parallel universe to Fate/Stay Night and tells the story of how, after the third holy grail war (that is the war before Kiritsugu Emiya and the events of Fate/Zero) the greater grail is stolen, leading to an attempt by the Mages’ Association to reclaim it. A seven on seven greater grail war ensues between two factions. For the original source material, you’ll need to learn Japanese or find some fan translations of the five volume light novel series.