In another Christmas tale from, really one of the best Short Trips books you'll find, just a shame it costs an arm and a leg, we get the Doctor in his Seventh incarnation delivering a letter to a war widow from her husband which leads to a flashback of a very special Christmas spent in the trenches where for one wonderful night the fighting stopped and men who were sent to kill one another for a few miles of mud came together in celebration of Christmas. It really shows just how powerful Christmas is that it can bring enemies together like how they wrote it in Christmas Truce. There's no plot to this, no big villain, it's just the Doctor observing one of the most significant moments of WWI alongside a soldier who he offers one chance to escape from all this but his sense of duty prevents him from doing so. Doctor Who has done this setting quite a few times but this one handles it perfectly.