Odd Girl Out by Timothy Zahn

This series started with Night Train to Rigel and I've enjoyed all of the entries so far. This one started with our hero, Frank Compton, being greeted in his own apartment by a girl aiming one of his own guns at him. She wants his help but she's going about it all wrong. He's tired from a long journey and just wants to sleep. He throws her out and is awakened four hours later by the police because she's been killed with his gun. When he's bailed out, he's back in the race against the group mind known as the Modhri along with his sometime partner McMicking and Frank's gal pal Bayta. It's a long rail trip against the bad guys and it ends up pretty obvious that there's another book on the way.