The protagonist in this little tale, Matilda, may turn out to be the thirteenth immortal. She was created, it seems, by her brother, who is a genius in the art of stitching living beings together (there seems to be some overlap with ideas from Monk's other steampunk series). Her father and mother were both killed by House White for illegal medical experimentation, but so far the houses have found her brother useful. At present, however, he is being held captive by Orange in a plot to give the head of Orange immortality. When one of the immortals from House Silver shows up on the scene, badly wounded, it triggers a series of events that will draw Matilda into deeper conflict and entangle her in the inter-House plotting and jostling for power.
"Is it contagious?"
"Hardly anyone gets it."
The jury is still out. I'll put the second book on hold at the library and see if it goes anywhere fun.