"The King of Lochlin's Three Daughters" (Scottish Gaelic: Sgeulachd Air Nigheanan Righ Lochlainn) is a Scottish fairy tale collected by John Francis Campbell in his Popular Tales of the West Highlands, listing his informant as Neill Gillies, a fisherman near Inverary.
A widow's oldest son asked her to bake him a bannock and roast a cock, because he would go to cut wood to build that ship.
The third giant said they should have not have the king's daughter until the youngest son agreed to be his slave for a year and a day.
He blew the whistle to have the eagle fetch him gold and silver clothing from the giant's castle.
[1][2] The tale is classified in the international Aarne-Thompson-Uther Index as tale type ATU 301, "The Three Stolen Princesses": a hero - often having an animal parentage - finds two companions, climbs down a hole and rescues three maidens from their underground captivity; he is betrayed by his companions and trapped underground, but eventually finds a way out back to the surface - usually by flying on an eagle's back.
[3] The episode of the journey on the eagle's back is parallel to similar events in many fairy tales, where a hero needs to feed pieces of meat to the eagle (or another mythical bird) for the remainder of the journey, otherwise it will not complete its flight.
[4] According to Irish folklorist Seán Ó Súilleabháin, the name Lochlainn designates Scandinavia "in general".