This is the tale of the great Gaelic hero Fionn MacCool and why he sucks his thumb. It is also the story of the Salmon of Knowledge on the Nova Scotia Gaelic flag. Tales of Fionn MacCool were popular across the Gaelic world, from Ireland to the Isle of Man and the Highlands of Scotland. Scottish Gaels brought tales of Fionn MacCool to Nova Scotia beginning in the 18th century and transmitted them orally from one generation to the next as part of their Gaelic culture.

The tale is retold as a participation story, with gestures corresponding to nine “action words” in the story. As the story is read aloud, audience members can perform the matching gesture whenever they hear an action word. The book contains two versions of the action story: the first is in English, and the second is in English but with the action words in Scottish Gaelic. After the audience becomes familiar with the all-English version, the second version with Gaelic action words can be introduced. The actions are the same in both versions, acting as a bridge to introduce Gaelic words and increase awareness of the language.

The second edition has been expanded to include engaging new black-and-white illustrations and a version of the tale entirely in Scottish Gaelic.