In celebration of The Queen's 90th birthday, Penelope Keith travels to the four corners of the Union to venture behind the scenes of Her Majesty's official royal residences. Penelope continues her journey at the Queen's official Scottish residence, the Palace of Holyroodhouse, where she discovers a unique 1000-piece royal silverware service and steps into the ill-fated bed chamber of Mary Queen of Scots. Penelope also boards Her Majesty's floating royal residence, the Queen's beloved yacht Britannia and peeks into the Queen's private quarters. On the west coast of Scotland, Penelope visits Inveraray Castle and the Master of the Royal Household of Scotland. Penelope takes aim with some archers and meets the the Royal Falconer at Borthwick Castle in Midlothian.