The Assassin's Blade is a collection of 5 novellas that prequel The Throne of Glass. 
 I recommend reading The Assassin's Blade after starting the series so you can pick up on all the foreshadowing that occurs. I read the novellas after reading Heir of Fire, book 3 in the Throne of Glass series. 
 The Assassin's Blade follows Celeana Sardothien's journey as she rises in ranks in the powerful Assassins' Guild. She builds a relationship with fellow assassin Sam Cortland and takes on the powerful leader of the assassins Arobynn Hamel. The Throne of Glass novellas are action packed and filled with thrills that will keep you turning the page! 
 By the way - did anyone else read "My name is Celaena Sardothien and I will not be afraid" in the same voice you would say "My name is Inigo Montoya. You killed my father. Prepare to die."? No? Just me?