David M. Booher 
All-New Firefly #1 [PDF ebook] 

Captain Kaylee leads the crew on a heist that proves too much for their moral code, but when mercenaries steal the relics anyway, it turns into a recovery mission. Meanwhile, unexpected revelations about Jayne’s family and past further complicate things. But how will Jayne’s past collide with the crew’s desperate present, especially when it leads them to steal from not the thieves den they had in mind…