What are these flowers?

Shot with my new Canon PowerShot S90.

I know, I know, this blog is on hiatus. But, trimming a yew at my front entry, I noticed this flowering plant hiding under the dense, green foliage. It wasn't there last year and neither my wife nor I planted it. So, what is it? It sure is pretty.

Note how the reds and greens really pop. This is because they are complementary colours which means they are opposite each other on the colour wheel. The use of complementary colours is intrinsically a high-contrast approach.