It is Bobby’s 100th birthday and Nurs Nansaidh has arranged a visit from Banrigh Ealasaid. Ceitidh Cocaire has made a big cake for him, but unfortunately, the cake has vanished. The Bowmore Crimebusters (Seumas Bond, Mairead Anna Marple, Eachann Poirot and Sin agad e Sherlock) are called in to get to the truth of the matter. Meanwhile, PC Plod suspects two dodgy characters Seonaidh Seòlta and Coinneach Carach, when his own cake goes missing. Mairead Anna Marple hatches a cunning plan to catch the cake thief and when the new sgoil-àraich is opened by Banrigh Ealasaid and the magnificent cake also goes missing, the real thief is brought to justice and the truth is revealed.