It is 1918 and Matthew and his troops are involved in a major battle. Both himself and William are seriously injured when a shell explodes near them and must get to a hospital as soon as possible. William is taken to Leeds whilst Matthew is sent to Downton Village.
Amazing acting by Dame Maggie Smith as Violet struts her stuff and excellent work by the extremely talented Michelle Dockery, well supported by Laura Carmichael, Sophie McShera and others who all do a great job showing us the horrors of war.
If you haven't seen this yet, I suggest you put it on your list of things todo immediately. You will be very glad that you did.