I can definitely recommend "Molecular Biology of the Cell", which is a undergrad-level textbook about cells. The latest edition is always very expensive, but you can get older versions cheaply. Link: https://www.amazon.co.uk/gp/product/0815341067
If you're a programmer and think 10 million lines of code constitutes a complex system, reading about how cells work on a molecular level should be humbling.
I haven't read it personally, so I can't vouch for it, but I've seen it recommended as one of the go-to texts for those interested in the biophysics of cells.
[0] http://www.amazon.com/Physical-Biology-Cell-Rob-Phillips/dp/...