Spoiler alert: This post is part of an in-depth discussion of The Hand of Oberon by Roger Zelazny, which will inevitably reveal key plot points. I recommend you support your local bookseller or public library, and read the book first.
Late with this one. Sorry! Forgot to publish.
Corwin travelled to New York in our Shadow Earth to retrieve the Jewel of Judgment, which he had hidden on his property there, only to find his brother Brand had beaten him to it. With the help of his sister Fiona, Brand's erstwhile ally, he travelled to the primal Amber, where he narrowly prevented him from attuning himself to the Jewel on the proto-Pattern. Brand completed the Pattern and escaped with the Jewel, however.
In this chapter, Corwin finally meets his nephew Martin, who has been brought to Amber by Random. Martin tells his own version of his story, which is consistent with the other Amberites' speculations about what happened to him. After walking the Pattern in Rebma, he used it to transport himself to Avalon, where Benedict taught him to use his new powers. He wandered in Shadow for years. Then, en route to visit his friends, the Tecys, he was contacted out of the blue by Brand, and stabbed. Before Brand could finish the job, Martin managed to break contact. After recovering somewhat at the Tecys', he again disappeared into Shadow, where he encountered the black road. He also met Dara, who pressed him for information about Amber, particularly about Benedict. Later, Random found him and brought him back to Amber.