Princess Ruby of Hearts is a role in one version of the Alice in Wonderland pantomime. She is the King and Queen of Hearts' daughter.
When she was a child, her father promised her to marry the Knave of Spades who wanted to marry her to become King. Ruby argues with her father and asks him not to make her marry him, but his mind was made up until the Queen made him promise his daughter she didn't have to marry the Knave. As she grew up, she fell in love with Prince Jack of Diamonds and he her. They become engaged.
In the pantomime, everyone is excited because of the impending royal wedding but the White Rabbit is running late ("I'm Late"). He has to get there on time to give the Kingdom of Hearts the golden heart which will insure Wonderland will be safe forever once it is placed on the shield with the other suits. The King and Queen meet the Joker and his new "friends" Alice and her mother, Millicent (or Milly). After the Joker saves their lives by implying some dark humour, the Queen invites them to dinner but they must find their own way so the Joker leads them to the castle. The Queen, upon learning the White Rabbit has no sense of direction, sends the Joker, Alice, and Milly into the forest to the wizard's gold mine for another heart.
Meanwhile, Ruby and Jack spend some time together the day before their wedding and Jack sings a song for her entitled, "I love you" and she joins in at the end. He then says he must leave to hunt wild haggis, and Ruby replies, "But what if you're hurt? I couldn't stand it if you were ambushed by a deranged haggis." Jack tells her he'll be save in the royal helicopter and leaves.
Milly tells the Knave that the Princess of Hearts and the Prince of Diamonds are getting married. Realising his promise has been stepped back on, he realises now he must stop the Rabbit and get the golden heart from him. Tweedledum and Tweedledee are hypnotised by the Knave into capturing the Rabbit. Once they do, the Knave takes the Rabbit's watch and the heart and when he puts them both in the cauldron, the heart turns black and the watch, unbeknown to him, becomes a time machine.
Later, there's still no sight of the Joker, the Rabbit or Jack and Ruby gets worried. She enters the forest in an attempt to find him, determined to know if he's okay.
Meanwhile, the Joker, Alice, and Milly find the gold mine ("Workin' in the Gold Mine"). The wizard gives them another golden heart and, since he has no power outside of the forest, he gives his hat to one of the miners, named "Harry Potter" who will become the new wizard. They're just about to set off when Jack enters, gun on hand, claiming he was just ambushed by a haggis and he's lost. The five of them set off for the Kingdom of Hearts. Ruby finds them and Jack, excited to see her, tells her they're both lost now. Ruby claims she'd rather be lost with him than live without him.
The wizard discovers he doesn't know the way after all as lots more trees have grown since he step foot out of his gold mine. Some hippies, who the Joker met before and gave his useless Sat Nav to, find them and are able, using a stick, to find their way out.
The Knave arrives at the shield, ready to place the black heart on it and gain control. The King and Queen are horrified. Then, leaded by Ruby, the others appear. The White Rabbit, who has also found his way out, reveals he has discovered his watch is now a time machine. The Knave, using the heart, freezes him. Jack tells the Queen and King that he will finish the Knave and is about to shoot him when he, too, is frozen to Ruby's horror. The Knave promises to turn anyone else into stone. Alice then stamps on the Rabbit's watch which explodes. The Queen is able to put the new golden heart on the shield. Jack and the Rabbit are returned.
The next day, Ruby and Jack marry and they sing their own song during which Jack swings her off her feet and carries her away.