Vagabond by Tim Rangnow

The solar system is stuck in a decades long cold war between the two major powers on Earth. Luna is torn between two allegiances, with each superpower controlling a dome on the home world's moon. In the asteroid belt, six mining colonies govern themselves. In the midst of it all is the Transport Guild.

Erik Frost is the captain of a guild freighter. He took command when his father died four years ago, left with large debts and a rattling old ship badly in need of an overhaul. When he is offered a mysterious job with few details and a high payout, he can't resist the opportunity it represents. He and his crew head deep into the system for the asteroid belt to deliver their cargo, unprepared for the dangers they would soon face.

They say some things are too good to be true, and this job could be one of them.