The Dragon on the Border picks up about six months after The Dragon Knight. With the arrival of spring it is the duty of Jim, Brian, and Dafydd travel to Northumbria to tell the next of kin about Giles de Mer being killed. When they get there they see that Giles, being a silkie, was still alive, but if he's killed as a man again he won't be able to escape his fate once again. That's the good news, the bad news is there are these Hollow Men that are wreaking havoc on the border. The Hollow Men are a ghost that can take a corporeal form, as long as at least one of them survives, they can only be killed for for a 48 hour period.

The French have conspired with the Scots to start a war on the border. The plan is for the Scots to use the Hollow Men to be their front line of attack, to throw the English into disarray, then the Scottish force will attack. At about the same time the French will attack England from the south.

Jim has to figure a way to eradicate the hollow men.

This series is excellent. I have previously read the next two books in the series. The first five make me want to read the others, and also maybe go back to The Dragon and the George and reread the first couple of chapters to see how Jim and Angie got back to 14th century England.