Something getting to my euonymus and hydrangea

Hoping someone can help me - a few weeks ago I noticed my euonymus was losing some of its leaves. I assumed it was just a bit of frost damage at first, but I've noticed that the problem seems to have spread to a nearby hydrangea. Can someone tell me what is wrong?

I don't know if you can see in the photos, but the hydrangea leaves have some little white spots, then they blacken and die. The euonymus seem to start with little brown patches and then go completely brown and drop off.

Thoughts?