Arbovitae Thuga Green Giants might work. They are tall and narrow and fast growers. Google Image to check them out. We planted a tree line on the side and rear yard and they are doing quite well. The deer will not touch them; however, they do eat the Arb Emerald Green which i now regret ever planing.

I'm not too clear from your description--is there a clear drop from the edge of your property, or is the retaining wall a raised wall to keep the adjoining property from encroaching?

Kerria is a bit bamboo-like in appearance, in that it forms clumps; the base is usually narrower than the top. It gets a yellow flower in the spring along the straight stems, and the leaves are an attractive lance shape.

To keep it from spreading too rapidly, the soil should not be too rich.

The stems are not all that strong, though, if you are looking for a barrier to keep someone from falling off an edge.

It is fairly fast growing compared to some shrubs, and you can expect it to reach at least six feet in a few years. If it gets ragged looking the worst stems can be cut off almost to the base, and that seems to make it fill in better the following year.

If you have pots or something to place in front of it it will look better, as it is rather bland unless used to set off other things.

It can spread and be a thug in some conditions, so if it interests you I'd ask around a bit for your location.

If you mean evergreen in the sense of pine trees, etc. I think there is a special section for that...

Something else, which grows more slowly, is Rhododendrons--again I would go to the Rhododendron section, though.

You didn't say how high you want the screen to be....

This is a comment about Dorry's suggestion of the Arbovitae Thuga Green Giants.

I understand the desire for a quick growing plant for screening purposes, but those things grow to 30 feet tall with a 12 foot spread. If you are planting on a couple of acres, that's one thing, but on the average residential lot, they are seldom a good choice long term. They block the sunlight, possibly for your neighbors who don't want the shade, cost a small fortune to have removed, and grow far taller than needed for screening purposes, overwhelming the area they are in.