Does the service actually play on the themes of light and dark? Or is it more of a metaphor/symbol?

Well, both. There are sections called Nocturns and Lauds. In each section there are readings.

With each of the 15 readings, a candle is extinguished in the church until there is only one candle burning: hope for resurrection.

Last night was an "experimental" service. Fr. Thomas had a series of movie clips/videos/art renderings that accompanied each reading.

Nice! Sounds very engaging!

@bgoodwin wow, sounds wonderful. I'd like to see that sometime.