Talk:The Enemy (series)/@comment-78.97.4.99-20151221072852

hi there! i'm a new reader and unfortunately i bought the 4th book-the saccrifice- instead of the first one. i have some question: are this books having some important chronological events that i am supposed to know before i start  reading the 4th book?( i can't find the first so....)they don't have the same characters? are they having something in common? (i'm sorry for grammar mistakes)