Sign of the Unicorn is the third book in the Amber series by Roger Zelazny.

This is *the* book of the series of five. Much of the action is intense and characters reveal more here.

War and treachery have come to Amber. King Eric is dead, but Corwin is distrusted by his siblings and yet will protect the throne. Little is as it seems -- as everyone has some reason to be less than helpful to Corwin. Corwin begins to find his obsession with the throne is a two-edged sword that may cost him his life, as it has his brother's. A walk into the city of Tir-na Nog'th leads to more questions -- and danger materializes as ghost visions become real.

And the deadly Chaosians are pressing their invasion. Will the royal family survive or perish?