Tepper has created in this book an interesting caste-ridden society, with its own power plays and intrigues, and managed to weave it into the world of the True Game rather well. I think she's solved a dilemma that is probably quite common to writers, "What do you do with a new idea when you've got readers clamoring for the same old world and characters?". SST just files off the square corners to fit the new world into a round hole in the old one, and lets it be "discovered" by a familiar face. It works, too.
Near the top of this society she's created are the hereditary Bridgers, those whose skills open up new territory for the people of the Chasm. Over hundreds of years, they've created seven cities there, from the broken bridge at the top to the lost bridge near the bottom. There are three Bridger families in the chasm, and one of them is willing to go to any lengths to be the most powerful, including murder.
When Mavin's sister becomes pregnant by the priest of the Birder caste who has been set to care for her, the resulting disruption allows the nasty Bander family to take advantage of the unrest to make a power play. Also, at this time, there have been several incursions from some slimy beasties from way down in the bottom of the chasm, so Mavin and her allies set off for the bottom to: a. evade the Banders. b. destroy the beasties. c. defuse the religious controversy generated by Handbright's pregnancy.
Their journey to the bottom, and the interesting things they find along the way, make this one an even better read than Song, I think. The tale is told for a while from some other points of view than Mavin's, and Tepper does a pretty good job of creating a new and weird society, warts and all. Again, a nice light fantasy novel providing a good evening's read.