Wee Gillis spends half the year with his father's rough and rawkus highland people and the other half with his mother's gentle sheephearding folk. But it's up to him to decide where he fits in.

Littlejack has a map that indicates the existence of a treasure on a far island. Black has a ship to get there. So they team up and sail off on Black's vessel, the Aeiu-a name based on all the vowels except for O.