Thunderbird

My final reading for 2015 was Jack McDevitt's latest novel, Thunderbird. It will be my pleasure to review it -- spoiler-free.
Thunderbird is the sequel to McDevitt's 1996 novel Ancient Shores (that I haven't read, and that was absolutely no problem). In the first book, an ancient portal to other -- and unidentified -- worlds was unearthed on territory within North Dakota administered by a Sioux tribe. Confrontation between the federal government and the Sioux has left the portal under the cont...