Although physical travel between the stars is impossible because of the vast distances involved, communication is instantaneous. There are a couple of different ways to visit alien worlds: veering (using virtual reality to project images), and teeping (using telepresence to control robotic bodies on the other planet). It's even possible to engage in trade, licensing the rights to books, art, inventions, and other intellectual property.
Deborah Rabinowitz is a literary broker. She veers to alien worlds and sells the publishing rights to Earth books. But when an alien is murdered right before her eyes, there's no way she can keep from being involved and solving the murder herself.
Then, when an old friend is accused of a murder on a different world, Deborah has to become a lawyer and defend her friend before a kangaroo court by solving that murder, too.