I look upon Slater's book as quite a different beast to most works on Nicholas II's death, because it is more an academic examination of the narratives and portrayals than an attempt to get to the bottom of what happened - though obviously she has a view.
She makes a straightforward summary of how the secrecy and criminal nature of the Tsar's execution gave rise to Romanov pretenders, martyrdom, romanticism, myth, etc., But then she takes this summary and projects it backwards, as if the actors then had some notion of what might happen now (Were that so then no one would have bothered with a revolution to begin with). For instance she claims that Lenin would never have ordered the execution because he would have known this modern outcome, and further he would have cared! It is, in my humble opine, a preposterous idea.
I bought Helen Rappaport's book because people spoke so highly of the way she evoked the atmosphere in the Ipatiev House, and was just porrfing my own novel on Alexandra and wanted to compare. I'd certainly had no intention of buying any more Romanov murder books - but it was truly excellent; it flows very well and I read it one sitting.
I was equally skeptical, particularly by the title which seemed rather cheeky. I really liked it.
With that in mind I'm going to stay on topic by recommending three titles for new readers interested in the details of the execution and final days in Ekaterinburg:
1. Last Days of the Romanovs - Wilson 1920.
The circumstances of an execution on the eve of losing a city to the whites makes Wilson's book a fascinating - albeit heavily and sometimes alarmingly biased - account. The reason I recommend it is because the testimony within (particularly that by my favorite fellow Iakimov) is so frequently manipulated (err, I mean cited) by contemporary writers. So it helps to read it on your own, and then dive into the other accounts. It gives you a leg up, so to speak, without having to investigate every primary source (though that helps too!).
2. Fate of the Romanovs - King & Wilson
Yes, controversial. I am not a fan; I make no attempt to disguise that. Nevertheless it is thorough and meticulously referenced. Cull through the more sensational conclusions (hint - where King falls into persuasion, read very critically) and draw your own.
3. Last Days of the Romanovs: Tragedy at Ekaterinburg - Helen Rappaport
Provides balance to #2, a mildly different perspective, and generally well written account. No citations, but sources are essentially the same.
From these three sources alone you will receive a well-rounded enough picture, or enough at least - for most of us on this board - to whet the appetite!