Anyone who has read much of the Darkover series knows who Varzil the Good is. Zandru's Forge tells the story of how he came to the Towers and worked on creating the Compact that would someday stop the use of laran in war.

Varzil wishes to work in the Towers, but his father sees him as weak and good for nothing, and refuses. Varzil appeals to the tower, but because his family, the Ridenow, are not popular with many of the other Domains, the Tower feels they cannot risk angering his father. Only Carolin Hastur, then a student at Arilinn Tower, feels that Varzil must return. When word comes from Varzil's home that his brother in in trouble, Carolin loans Varzil and his father an aircar to get home quickly.

Varzil rescues his brother with his laran, and his brother takes his side in his request to work in the Tower. So begins Varzil's life in the Towers, with Carolin as a good friend.

Not all is well. Carolin has a friend, Eduin, who appears jealous of any attempts Varzil makes to be Carolin's friend. Eduin is the son of Rumail Deslucido (although no one in the Tower knows this), and is sworn to kill Carolin. He finds the job difficult because he truly likes Carolin.

Some of the scenes in this book come from Hawkmistress , and this book explains how Carolin came to be the exiled King in that book. 

Carolin is not Eduin's only target. He also seeks the daughter of Queen Taniquel from the previous book in this trilogy. His life is ruled by plots of revenge for his father, uncle and cousin, taking precidence over his own feelings. He is little more than a tool for his father's frustration.

As luck would have it, Felicia Darriel has also come to Arilinn Tower, and she and Varzil fall in love. However, she leaves to train as the first woman Keeper at Hestral Tower, as Arilinn is too bound by tradition to allow her to use her gifts to the fullest. It is there that Eduid plots against her.

This book is a fascinating chance to learn more about Varzil and how the Compact came to be. It is a time of near constant wars between various small kingdoms, and horrific weapons are used freely.