The recently widowed Mary Stuart returns to Scotland to reclaim her throne but is opposed by her half-brother and her own Scottish lords.
| Actor | Role |
|---|---|
 Katharine HepburnMary Stuart | Mary Stuart |
 Florence EldridgeElizabeth Tudor | Elizabeth Tudor |
 Fredric MarchBothwell | Bothwell |
 Douglas WaltonDarnley | Darnley |
 John CarradineRizzio | Rizzio |
 Robert BarratMorton | Morton |
 Gavin MuirLeicester | Leicester |
 Ian KeithMoray | Moray |
 Moroni OlsenJohn Knox | John Knox |
 William StackRuthven | Ruthven |
 Ralph ForbesRandolph | Randolph |
 Alan MowbrayThrockmorton | Throckmorton |
 Frieda InescortMary Beaton | Mary Beaton |
 Donald CrispHuntly | Huntly |
 David TorrenceLindsay | Lindsay |
 Molly LamontMary Livingstone | Mary Livingstone |
 Anita ColbyMary Fleming | Mary Fleming |
 Jean FenwickMary Seton | Mary Seton |
| LLionel PapeBurghley | Burghley |
 Alec CraigDonal | Donal |
 Mary GordonNurse | Nurse |
 Monte BlueMessenger | Messenger |
 Robert WarwickSir Francis Knollys | Sir Francis Knollys |
 Halliwell HobbesMan (uncredited) | Man (uncredited) |
 Nigel De BrulierJudge | Judge |