This story occurs immediately after Holden makes his announcement that the ice hauler was destroyed and a piece of tech with a Mars stamp on it was discovered.
The Cassandra is flying hand to mouth already and they realise that with the coming price fluctuations they won’t be able to continue flying. So they go off to an asteroid in a last attempt at turning a profit: finding something that could change everything for them.
A good little story that i would suggest reading as soon as the Holden announcement goes out, or, you could wait until the end of Leviathon Wakes and read it then.