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My poor Gennaro, in his wild and fiery days, when all the world seemed against him and his mind was driven half mad by the injustices of life, had joined a Neapolitan society, the Red Circle, which was allied to the old Carbonari. The oaths and secrets of this brotherhood were frightful, but once within its rule no escape was possible. When we had fled to America Gennaro thought that he had cast it all off forever. What was his horror one evening to meet in the streets the very man who had initiated him in Naples, the giant Gorgiano, a man who had earned the name of 'Death' in the south of Italy, for he was red to the elbow in murder! He had come to New York to avoid the Italian police, and he had already planted a branch of this dreadful society in his new home. All this Gennaro told me and showed me a summons which he had received that very day, a Red Circle drawn upon the head of it telling him that a lodge would be held upon a certain date, and that his presence at it was required and ordered.
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Pardon my quoting so much. IT in red refers to A SUMMONS, but is it correct to say the red sentence means the sign, whatever it might be, of the organization called Red Circle is drawn on (shouldn't it be AT?) the top part (=head) of the paper, which is a summons (=call, order etc.)?

The head of it