Captive Star by Nora Roberts

Stars of Mithra, #2 -- A bounty hunter, Dakota, thinks he is in for an easy take and is quite surprised.  It turns out that it is not as easy as it seems.  M.J. takes him down and quickly puts him in his place.  They both end up get run after and shot at not really knowing why.  They get very close to finding the answers, but not before the people that had been chasing them die.  M.J. gets back together with her friend Bailey, who had sent her a gem stone and is relieved she is okay.  They still need to find Grace who has the last stone.  And of course, in true Roberts fashion Dakota and M.J. fall in love.