In Amongst the Marines, Steven Preece vividly depicted his excessive, violent lifestyle as an elite Royal Marine Commando. Now Always a Marine covers the author's struggle to leave that lifestyle behind following his departure from the service.

Back on civvy street for the first time in over seven years, Preece finds it extremely difficult to adapt and struggles to shake off the belligerent mentality he developed while in the Marines. Despite these difficulties, he marries and starts a family, but this positive change is not enough to turn his life around.

Preece soon discovers that his tendency towards violence will not be tolerated in the civilian workplace and, after finding himself blacklisted by many companies in his area, he is forced to look for employment abroad. This quest for work takes Preece to France, where he is caught up in a hotel fire; Germany, where he is double-crossed out of his job and later teams up with an ex-SAS trooper; Morocco, where an incident lands him in jail and he is later shot at by border police; and Thailand, where he fights in a boxing ring with a former French Legionnaire and gets caught up in a business scam.

Having settled back in the UK, Preece's behaviour remains excessive. He severely injures his head and suffers minor brain damage after a heavy-drinking session. Upon recovering, he looks for something else to believe in and begins training in ninjutsu, the martial art of the ninjas, who view aggression as a sign of weakness. This, combined with the love of his family, finally enables him to put his past behind him.

Always a Marine is the action-packed, often shocking account of one ex-Marine's 13-year struggle to control the aggression he learnt as a serviceman in order to become a respectable civilian.