This is another of the 50th Anniversary books re-released in 2013 (I’m a year behind, I know).
It’s Christmas time, and the Doctor, Amy, and Rory are supposed to be heading home (to Leadworth, that is) for Christmas. But of course they are sidetracked to where they’re needed (thanks, Idris/Tardis!). They end up somewhere Earth-ish, and it’s definitely winter. When they’re exploring, Rory turns back to get a warmer coat. (Why does he do that? He should know better than to get separated from the group). Amy and the Doctor meet the locals, the Morphans, who are out searching for a missing girl. They’re taken into custody because they’re strangers (that happens a lot, doesn’t it?), but they also escape. It turns out these people are colonists from Earth. The winters are getting colder, and people are disappearing.
Meanwhile, Rory is looking for Amy and the Doctor (as ever), but instead finds scary things in the woods and yet more Morphans. The scary things chase the Morphans and shoot energy blasts at them. Rory hides in an abandoned building, and finds the missing girl. They head back to town and try to set things straight.
The scary things in the woods turn out to be Ice Warriors, looking for a new home (that also happens a lot, doesn’t it?). The Doctor and the Ponds try to fight them, with some help and also some interference from the Morphans. I’ll leave it to you to figure out if it all works out in the end.