Crossing the Dark Sea" (written and composed by Michael Symmons Roberts and James Whitbourn.) It's available for seven days as usual.
So it features the Ninth Doctor and the singer from "Jumping the Shark: Doctor Who edition"...yes, all right, "A Christmas Carol". Jenkins' part is rather better here than it was in that story, being composed of singing. And it's only half an hour: the story is a good one on its own merits (a melancholic reflection on war, interspersed with all too vivid period details), and would be worth a listen regardless.