The Enemy is Lee Child's eighth Jack Reacher novel, but the first that takes place during his time as an Army M.P. major. The first seven books gave many hints about his time in the Army. The Enemy features the same Jack Reacher we have come to know and love, who does what is right, even if he knows there will be consequences. The Reacher who always seems to bed beautiful women, but never gets attached. The Reacher who "said nothing." The Reacher who puts the pieces of the puzzle together against the odds.
The differences are striking, and sometimes amusing. This Reacher in The Enemy is under command. He goes where he's told--except for those times when he doesn't go where he's told. This Reacher will sometimes throw out clothes rather than wear them again, but, since he's serving in active duty and all, he actually carries luggage when he travels! (Readers of other Reacher books will get that this is a big deal.)
In The Enemy, Reacher investigates the death of a general--until he is told not to. But he does anyway. Then a soldier is murdered on base, and he investigates that--until he's told to falsify the investigation. But he doesn't. His new superior officer tracks him down to have him arrested for going AWOL, even though he really wasn't. But Jack, being Jack, manages to escape their clutches.
The Enemy shows Jack as the other books don't, as an official investigator, rather than a lone operator, vigilante type. I won't be giving anything away when I tell you Jack figures it all out in the end, and is vindicated for his disobeying orders, for the most part. Jack's conclusions lead him to a great deal of disillusionment with the Army. Even though he's still in at the end, Child set him up for a break at some point. I noticed the new Reacher novel, to be released in November, is set before Jack leaves the Army. I look forward to seeing what else we learn about Reacher in uniform.