Tosca has the subtitle 'Melodramma in Three Acts' and even by the eye-rolling standards of Italian opera, it packs an emotional punch. Extreme religion and power politics mix familiarily with a fatal double of love and lust. All the principles, villain, hero and heroine lie dead at the end. Baron Scarpio is murdered, Mario Cavaradossi is executed and Floria Tosca commits suicide. Her jump from Rome's battlements has long been one of opera's most celebrated endings.

Based on a play of the same name by Sardou which starred the great Sarah Bernhardt, Tosca was premiered in 1900. Ever since it has been a huge popular success, although the authoritative American musicologist, Joseph Kerman, dubbed it a 'a shabby little shocker' updating it later to 'a chain-saw movie.' What he failed to acknowledge is that the tight structure of the play, with only three main characters, and the terrifying forward march of the music sweeps aside any scruples about its exaggerated subject matter. When well performed, as of course it is at the Royal Opera House, this is Art at a high level.

In fact the story is not so simple. The noble Cavaradossi, sung by Riccardo Massi, is a republican and lives for art and love of Tosca, the great diva, played by the great diva Martina Sarafin. Cavaradossi is painting a fresco in church when he finds Cesare Angelotti, sung by Simon Shibambu, an escaped political prisoner in hiding. He leads him off to hide in his villa. But his beloved Tosca suspects a woman is involved and Scarpia, the wicked Chief of Police, sung by Marco Vratogna, who is searching for Angelotti, cleverly plays on Tosca's jealousy, rightly guessing she will lead him to his prey.

This first act, important in setting up the characters and whose music already hints at the darkness to come, was on the night I saw it, slightly less than compelling. Massi took his first beautiful aria, very slowly and the two lovers seemed to bicker more like young marrieds than passionate lovers. On the other hand this opening is always going to suffer in comparison with the unfolding horrors of the next two acts.

In Act two Scarpia is in command, the scene removed from church to the Palace Faranese. Angelotti is dead, Cavaradossi captured and Tosca come to plead for mercy. Scarpia's only answer is to tell his men to lead his captive away to the torture chamber, close enough for Tosca to hear his agonised groans. The power of this scene comes most of all our belief in Scarpia's evil intent. He is in a sense the pantomime villain, except that such men did exist in Rome during the turbulent Napoleonic era.

Vratagna has played the part often before and perhaps no longer feels the need to over impress us with the force of his cruelty. The confidence in his singing makes it clear that he will have Tosca's body and her soul is of no interest to him. Tosca naturally has a different point of view and her agony dominates the stage. Must she commit murder to save her lover? To save herself? Her triumph as she believes she has outwitted Scarpia, lying dead between the two candles she has placed at his head, sets up the final scene with passionate intensity.

The third act, as the terrible trick played by Scarpia slowly plays itself out, is the most perfectly realised. The heavy phsyicality of the sets in the first two acts gives way to something starker and less defined. The stars are beckoning Cavaradossi outwards, calling him away from the life he loves, even as he cries he doesn't want to die. Riccardo Massi, singing of his love, of beauty and nature, seems already to have passed into another world. Serafin's appearance, her joy that has she saved them both - it will be a mock execution - Scarpia had told her so - seems childishly hopeful. How could she believe she could outwit Scarpia, the professional dealer of death? In these moments both singers rise to tragic heights.

So, heroic Cavaradossi faces up to the firing squad and we, the audience, watch in agony as the guns sound and Cavaradossi lies where he's fallen, unhearing of his lover's encouragement that now he can safely rise. The rhythmic tempo that has sounded throughout the opera has turned into a funeral march and any misgivings I might have had about Placido Domingo's conducting in the first act are thoroughly vanquished. He has brought it off magnificently.

This Royal Opera House production by Jonathan Kent was first seen in 2006 but still embodies all the darkness and dangers of a city where church dominance is supreme and order is kept by men like Scarpia. It was no surprise that the auditorium was completely full, despite, it is my duty to note, serious improvement works going on above the Floral Hall. However I would suggest that tickets are withheld in future from my neighbour, a pretty young woman who devoted herself to taking selfies whenever the lights came up. Scarpia would have known what to do with her.

TOSCA by Giacomo Puccini
Conducted by Placido Domingo
Directed by Jonathan Kent