While the book is marketed as a stand-alone novel, it quickly becomes evident that Sea Lark is the sequel to an earlier volume, Mother Ocean, Daughter Sea. If you have not read that one, you don't have much chance with this one, but you won't really want it. Much like with any recent Katherine Kurtz Deryni novel, Ms. Marcellas is so concerned with her world's politics as to bore a reader to tears. Admittedly, more actually happens than in the new Deryni novels, but it's not written as well. Either way, you don't care much. Not only is the politics thick and fast, the actual political hierarchy is not explained until most of the book is past. If you don't already know your Dukes, Counts, and Barons by heart, you'll have little chance of following the structure, especially with the vaguely defined High Lords thrown in for additional complication. The magic system is modestly interesting, as are the central characters, but it never really gets beyond that.
Finally, a note on the title. In case you should miss it, the sea lark is here used as a metaphor. On virtually every page. This world is suffering from a serious sea lark overpopulation problem, and soon there's going to be a crash. Don't wait around to see it.