Yes I was reading a new Tim Powers boook while listening to an old one. Don't ask me, these things just happen. 

Vickery and Castine are once again thrown together in and around the haunted freeways of Los Angeles, once more desperately trying to save the world, this time from aliens. With crop circles and monstrous figures and columns of ice and thousands of metal spheres appearing all over the place, but especially near out time-shifted duo, it becomes apparent that extra-dimensional aliens - rather like the entities in Medusa's Web - intersect with our reality and immediately die. But this is a haunted world, and their ghosts are restless and they want out, but that will mean catastrophe for the planet. 

Pursued, as usual, by government agents, allied, as usual, with assorted weirdos, freaks and outlaws, they try to work out what is happening, when and where, and whether thay can do anything about it.

I think? this is a trilogy, and if so it's a grand finale, succesfully taking the premise of the series, and Power's perennial preoccupations with ghosts and odd corners of history and geography, to a new conceptual level while delivering the usual thrills and spills and chills.