Let this review cover both SPIRIT OF THE STONE and THE HEART OF MYRIAL, since I will not find the time to review both separately.
This is a very good fantasy series. It reminds me a bit of the Rosemary Kirstein series of Steerswoman novels in that it is fantasy with a science-fiction world for a backdrop. It appears that the world of the novels was set up in a perfect balance countless ages before by some super race. Climate was perfect, and various different races and peoples were set on different islands with barriers between them called "curtain walls.' Now the balance of this world has gone way out of kilter and the world is headed for destruction. Even now the weather is so bad crops cannot be grown and starvation stalks some of the lands.
In this setting, we have several most interesting characters on a dire mission, related to an effort by the "Shadowleague" to save the world. Naturally, there's a quest element -- the world cannot be saved if the heroes of the Shadowleague cannot come to a greater understanding of how the world got the way it is, and how it is controlled. Ironically, there is a scientific, central control center for the world which is totally misunderstood by the superstitious and ignorant peasants who now run everything. So this science center is NOW used as a magical temple for the priest class. I mean, sometimes you just want to THROTTLE these fools.
The character that is SO MUCH FUN and really steals the show is Kaz, the firedrake. This character is a pint-sized dragon. Bright red, covered with scales, and with the toothy dragon's jaws and head. HOWEVER, the firedrake is only about the size of a rhinoceros. Big, yes. But not huge, if you get my drift. The firedrake is an intelligent character in the story who communicates with telepathy. He is also a magical creature and a fire creature -- he can launch jets of intense flame for 25 or thirty feet -- the heat is enough to even melt metal. He also has quite a personality, always sneaking off to eat a sheep or two. I mean, this firedrake is a big guy, and those fires need to be stoked, you know?
Just for the record, the books have a few REAL dragons -- and I mean, these guys are really huge. Like about the size of a small freight train. Fortunately, to avoid going too far overboard on dragons and their firedrake cousins, the real dragons take something of a background role in the novels.
Great fun, fast moving, very imaginative -- and Ms. Furey writes VERY well. Some of the other reviewers have complained there's not enough action, but action is a trade-off against characters. To build interesting characters you need lots of dialog, and to supply this the endless action occasionally has to be put on hold. For my part, I think the balance between action and characters is pretty well maintained in the book.
I recommend both Heart of Myrial and Spirit in the Stone. Am looking forward to reading the third one ASAP.