I started to read this book from a standpoint of blissful ignorance, having been taught (outside the UK) that Roman Britannia ended at Hadrian's Wall. Living now in Scotland in the neighbourhood of a Roman Castellum, I had to realize that there was something to learn here, and I got a hold of this book for my illumination.
Turns out that the biggest event in the classic history is the battle of Mons Graupius, in which the first and only ever combined native force received a whooping by Gaius Agricola, a Roman proconsul legate, whose son-in-law, the famous Roman historic writer (historian would be a term by far too scientific) has immortalized this battle in his "Agricola".
There now sits the battle on the shelf of Scottish national consciousness alongside other famous battles like Culloden Moor or Bannockburn Bridge. With the added mystery that the location of the battle is not settled among historians and archaeologists.
This is where this book comes in. Good news is that its volume is very limited, compared to other historic tomes. It provides a critical narrative of the battle and its leader's chronicler's political implications and context, and that part is fine.
It then proceeds to make a case to locate the battle near a Roman waypoint Castellum near Perth, based mostly on textual evidence and Scottish/Pictish/Caledonian context. And that is where I was quite disappointed. The issue is the incredibly thin base of archaeological evidence. There is a whole chain of castelli known along the Eastern coast of Scotland, but very little is known about what happened there, when they were occupied, by whom and for what purpose. The book also casually mentions that the Roman legions were depending on supplies from accompanying Roman naval forces. But none of the infrastructure is established.
It is not the author's fault, but the overall very unsatisfying volume of knowledge surrounding the Roman presence in Scotland should require a huge Work-in-Progress banner across all works published on the subject. Makes at least me wish that my job was somewhere in that discipline, as it would probably see me safely through to my retirement.

A footnote: If you are interested in this book, a visit of the website http://www.romanscotland.org.uk (with which I am only affiliated as an impressed reader) should be worth your while as well ( )