The story is one of the best in the whole legendary, and the Church has never claimed it is history. Placidus, a general of Trajan, is hunting near Tivoli when a great stag turns at bay and he sees between its antlers the figure of the crucified Christ, who says: 'Why dost thou persecute me? I am Jesus, whom thou honourest without knowing it.' He is baptised as Eustace, loses everything in the manner of Job — his rank, his wealth, his wife to a ship's captain, his two sons to a lion and a wolf — is restored to all of it, and is then roasted with his recovered family inside a bronze bull for refusing to sacrifice.
No part of that can be traced earlier than the Greek passion from which the Latin versions descend, and the same vision is told of St. Hubert of Liege three centuries later. The acts were already regarded as fabulous when the Roman Martyrology was revised, and Eustace was among the saints removed from the general calendar in 1969.
What is old and certain is the cult. The church of Sant'Eustachio stands in the Campus Martius on a foundation recorded from the eighth century; the stag's head with a cross between its antlers looks down over its facade, and every hunter in Europe knows the emblem whether or not he could name the saint.