After 35 years in Chicago, Donal reluctantly returns to the Scottish Highlands to reconcile with his estranged older brother Sandy. Sandy needs Donal to take over the family's whisky distillery or he'll be forced to sell and give up on the family's legacy. But their reunion forces the brothers to confront the past and the real reason Donal left Glenrothan.

A happily engaged couple is put to the test when an unexpected turn sends their wedding week off the rails.

Having thwarted Bowser's previous plot to marry Princess Peach, Mario and Luigi now face a fresh threat in Bowser Jr., who is determined to liberate his father from captivity and restore the family legacy. Alongside companions new and old, the brothers travel across the stars to stop the young heir's crusade.