Curse of the Iris
by Jason Fry
"As Tycho and his siblings continue to compete for the captain's chair of the Shadow Comet, they must work together to hunt for an old pirate treasure--a treasure that is tied to some long-buried family secrets"--
Conduct of lifeBuried treasureSteampunkSibling rivalryFictionScience fictionSiblingsBrothers and sistersSpace shipsFamily secretsPiratesFamily