The Doctor will take on his most unlikely foe yet in this year's Doctor Who Christmas special.
The Time Lord (Matt Smith) has to battle with a flying shark as he desperately tries to stop a ship carrying 4,000 people from crashing to Earth.
Veteran actor Michael Gambon and opera singer Katherine Jenkins star in the festive episode, which is based on A Christmas Carol.
Gambon plays Kazran Sardick, a rich but lonely Scrooge character who controls the skies.
He has frozen Abigail Pettigrew (Jenkins) because her family cannot pay their debts, and it is up to The Doctor to influence their relationship and try to save the day.
Katherine said the programme makes for emotional viewing.
"I hope that people will also be moved by it and can relate to it.
"I didn't set out to make people cry over their Christmas dinner but it is heart-warming."
The role is Katherine's acting debut, and she said she will need "a large glass of wine" to settle the nerves when she sits down to watch it with her family.
Doctor Who will be broadcast on BBC One at 6pm on Christmas Day.