Sign of the Unicorn by Roger Zelazny

  Sign of the Unicorn is the third book in the chronicles of Amber. After arriving with an army with firearms when Amber was under attack and Eric lay dying, Prince Corwin is finally at the helm of the kingdom, for the moment. As the story opens, he has been made the prime suspect in the murder of his brother, Caine. He found a note ostensibly from Caine, asking him for a meeting in the Grove of the Unicorn, and when he arrived, he found his brother with a slit throat, killed by a humanoid out of shadow that seems extremely familiar. It's one of the same crew that attacked Corwin, Random and Flora at the beginning of Nine Princes in Amber.

Corwin returns to the castle with the body of the attacker, after placing Caine's body in a shallow grave, and calls Random to his room. He finally gets to hear the story of how Random ended up being pursued. Random was attempting to rescue their brother, Brand, from a strange prison in one of the wilder shadows at the edge of Chaos.

One amusing little passage about his first battle with Brand's jailers:

"Unfortunately, the inconsiderate lout had carried off my blade, snagged in some bony cleft or other he had chosen to interpose when I swung. It was obviously my day for losing blades, and I wondered if my horoscope would have mentioned it if I had thought to look before I set out."

After Caine's funeral, Corwin decides to take advantage of having most of his siblings gathered in one place  and, after having Random relate his tale, uses their combined wills to use the Trumps (powerful tarot cards that allow communication and transport between their wielders) to contact Brand and attempt to set him free. They succeed in this endeavor, but someone in the room attempts to kill Brand as soon as he is in the room with them, planting a dagger in his kidneys. Gerard uses his medical skills to keep Brand alive, and stands guard over him while the others return to their conversation and conspiracies.

When Corwin finally heads off to his room at the end of the evening, he is surprised by an assassin there, and only the effects of the Jewel of Judgement (which occasionally does odd things with time) keep him from being killed, as he manages to partially dodge the lethal blow, and the Jewel teleports him to a place where he subconsciously feels safe, his own bed in his house on the Shadow Earth. While he is there recovering (taking advantage of a time differential between Earth and Amber) he learns a lot more about the accident that put him in the hospital, and becomes more determined to get to the bottom of what's rotten in Denmark...er...Amber.

More good intrigue, and some things that were previously shadowy begin to emerge.