I have enjoyed the Fablehaven series and am delighted the Mull can continue the series with continued high quality. In this book Kendra is sent with a team to get a key to the next artifact (this is important in the overall series). The plot takes us outside of the New York sanctuary that is cared for by her grandparents.
If you are unfamiliar with the Fablehaven series, the important plot device is that there are magical creatures still living in the world, but they are primarily kept in "invisible" sanctuaries around the world. Kendra and Seth Sorenson (brother and sister) appear to be the likely successors as caretakers of the Fablehaven sanctuary currently managed by their grandparents. Of course, the forces of evil are trying to upset the balance of this arrangement. Kendra, Seth and others at Fablehaven are instrumental in fighting these forces of evil.
Back to Dragon Sanctuary... Of course, as per the title we are looking at a sanctuary for dragons in this book. Mull continues to engage the reader with plot and character twists that surprise the reader and will motivate almost all to continue reading.