Some authors just write about it. Chris Ryan has been there, done it, and lived to tell the tale.

This is the second in the action-thriller Agent 21 series by the real-life SAS hero. In the year since Zak Darke was approached by a shadowy government agency to become Agent 21, his world has changed completely.

But there is no time to reflect on this - the undercover operations go on.

Zak is sent to a port in west Africa, a known terrorist stronghold, under the guise of working ona charity volunteer project.

But charity work could not be further from Zak's real mission - he must sneak onboard an enemy ship, gather information - and then destroy it.

Never has Zak's training been more useful: Trust nobody.