It is the nature of Sydney Bristow's job to deal with some of the world's most dangerous criminals, but usually the end result is that they are taken out of circulation for good, and placed somewhere where they can cause no further harm.

So, when her latest assignment requires her to act as a terrorist, liaising with an international arms dealer and allowing him to walk away she naturally starts to question whether she is actually working for the "good guys".

When a new organisation ("The Thirteen") come onto the scene and murder the arms dealer and the scientist behind a terrible new weapon, she finds it difficult to accept Sloan's statement that they are just another group of terrorists and should be treated as such

Soon APO start to suspect that "The Thirteen" have an ulterior motive behind their actions. And, when they discover that the leader of the group is known to Sloan - and has good reason to hate him - they realise that they must act quickly to bring the group out into the open.

It is up to Sydney, in the guise of a freelance terror agent to act as bait. But will APO discover the true target of the actions of "The Thirteen" in time to save the intended victim?

Vigilance is another book in the Alias series of TV-tie in novels (it is written by Paul Ruditis). It follows the actions of Sydney Bristow and the APO team as they attempt to foil the plot of another terrorist group. This story, though, is a little different. Usually it is clear from the start that APO are working for the good side, but this time the lines are a little blurred. "The Thirteen" take out terrorists that APO are allowing to live - surely this makes "The Thirteen" good guys?

This book is also a definite case of "power corrupts, and absolute power corrupts absolutely", for when APO and "The Thirteen" each gains possession of one half of a terrible weapon, neither side is willing to destroy it to protect the world. Each wants total control of the weapon for their own group. Characters are forced to face up to their actions in the past, and it is evident that right and wrong are not as clearly definable as black and white.

This is an excellent story. It is full of action, it keeps you intrigued right the very end. The characters are faithful to their TV counterparts making this a must read for all Alias fans.

Synopsis
It bothers Agent Sydney Bristow's conscience that too often her job asks her to work with criminals she would much rather put away. She understands the logic - the lesser of two evils approach is all too familiar to her - but that doesn't make it any easier to accept. Someone else disagrees. APO's more dubious contacts are being assassinated, with only a calling card depicting a black star with the number thirteen in its centre for a lead. When it becomes clear that a lethal, highly trained vigilante organisation is interfering with APO's missions, Sydney must put aside her empathy and help shut down these mysterious "13 Stars". But when Sydney herself is mistaken for a freelance terror agent, she worries that the mistake is not so far from the truth. And now that she's marked, both her cover and welfare are in immediate jeopardy...