For me, it would have to be Robert K Massie's 'Nicholas and Alexandra' if you want a good, detailed read of the story up to July 1918. Most people on this forum probably started with that book at some early stage of their interest. Then you could follow it up with same author's 'The Romanovs : The Final Chapter', which takes the story up to 1998 (the burial of the family) and looks at all the impostors. If you want a photo book, my personal vote would go to 'Nicholas and Alexandra' ~ The Family Albums, by Prince Michael of Greece. Sadly it's hard to find and expensive when you do find it! I have spare copies of both the Massie books if you'd like them : send me a PM with your details if you would like them.