The plot of Der Zarewitsch is loosely based on a true story: the self imposed exile of the son of Peter the Great, Alexei, who shirked his father's command by running away to Naples with his Finnish mistress disguised as a page. The couple spent two years galavanting around until Alexei was compelled by his father to return. His father was paranoid that Alexei was conspiring against him and ultimately Alexei ended up being imprisoned and tortured. The Russian senate convicted him of conspiring against his father and he was sentenced to death. He died due to ill health before he could be executed, most likely resulting from the poor treatment he received while imprisoned.
Reichert's libretto differs on several points from the life of Alexei. First, he changed the story so that the young girl, Sonja, is first seen disguised as a male Circassian dancer. When the Tsarevich runs away with Sonja he believes that she is a boy adding what Richard Traubner of Opera News called an "underlying homosexual frisson" to the operetta. Eventually the young prince discovers that Sonja is in fact a girl disguised as a boy. The two fall in love and escape to Naples. A further major difference is that the operetta does not have such a tragic ending, though it is not exactly happy either. Eventually the Zarewitsch learns that his father has died and he knows his relationship can not continue with Sonja as he is now the Tsar. The operetta ends with a "bittersweet royal-commoner parting".