Apologies for the crowded photo. The plant in question is in the foreground, with the red-tinged foliage and prominent seed pods.

I'm not sure what the flowers looked like--they were all gone by mid-August when I moved into my house. Stems are 2-3 feet tall. Leaves and stems have been turning red as the weather cools.

Could it be Penstemon digitalis?

Some Penstemon species for sure; a photo of the basal leaves might help.