Italian castrato Farinelli (Sam Crane) soothes the troubled mind of Spain’s King Philippe V (Mark Rylance) who suffers from what the Diagnostic and Statistical Manual of Mental Disorders would code as a bipolar disorder. Despite support from the King’s physician Dr. Jose Cervi (Huss Garbiya), the Chief Minister of Spain Don Sebastian De La Cuadra (Edward Peel) advocates for the King’s abdication because of his assumed mental illness (“possession”). Philippe’s wife Isabella Farnese (Melody Grove) insists the King’s behavior is not due to a mental illness but “a disposition” that “will pass.” While in London, Isabella discovers Farinelli and brings him back, hoping his singing will somehow “cure” the King.

This remarkable story (based on fact), is the substance of Claire Van Kampen’s “Farinelli and the King,” currently running at the Belasco Theatre. Director John Dove’s staging gives the breadth and depth of Ms. Van Kampen’s script the “space” it needs to unfold and embrace the audience with its pathos and ethos. The scenes between Farinelli and the King brim with effusive energy, beginning with the scene where Farinelli first visits Philippe and awakens him with his singing (Iestyn Davies and James Hall alternate). Mark Rylance gives awakening to the recitative from Handel’s “Ho perso il caro ben” a truly mystical tone. And Sam Crane brings an authentic vulnerability to his role as Farinelli that counterpoints brilliantly with the tempered desperation of Mark Rylance’s Philippe.

Amidst palace intrigue and political shenanigans, the relationship between Farinelli and the King blossoms as Philippe identifies deeply with the famous maestro, comparing their “regal” identities and the concomitant “imprisonment” their “reigns” afford them. This consanguinity between “patient” and “healer” (an “affair” that parallels that of David and King Saul) thrives in the palace and in the King’s new “forest home.” Whether their relationship can survive La Cuadra’s attempt to send Farinelli away, or Isabella’s fondness for Farinelli comes into question.

The King’s death, Isabella’s mourning, and Farinelli’s new role in the palace consume the ending of the play and seem to need more detail to strengthen the narrative; but, the denouement is necessary to fully appreciate the importance of Farinelli in Philippe’s life and reign and how his voice “kept away the other voices” in the King’s head that threatened to undo him.

Jonathan Fensom’s design and Paul Russell’s lighting deepen the overall success of this new play. Although I expected to be moved more deeply by the singing of Handel’s arias, it is clear to the audience how Farinelli and the King walked together in distinction and in imprisonment.