Welsh National Opera provided a thrilling experience that few who saw it will forget in David Pountney's astonishing new production of Mussorgsky's Khovanshchina. A fitting climax to the company's spring visit to Milton Keynes, it offered a welcome engagement with the unfamiliar after four days devoted to the popular (Madama Butterfly and Carmen).

An unashamed innovator (many have still not forgiven his recent space-travelling version of The Flying Dutchman), Pountney does not let down his audience here. Eye-popping sequences include a bathroom tryst between the tyrannical Prince Ivan Khovansky (Robert Hayward, pictured) and a naked Persian slave (Beate Vollack). His intravenous shot of heroin is followed by a more terminal injection when he perishes, Marat-style, to a knife wielded by the shadowy politico Shaklovity. He is played by baritone Peter Sidhom, on superb form and one of the evening's few singers whose words are always intelligible in this English language version of the opera, offered without surtitles.

That long sections pass without the dialogue being fully understood is perhaps of no great moment, however. Mood and music are so much of what the evening offers, the latter wonderfully Russian in this orchestration by Shostakovich - all ringing bells, martial trumpets, and stirring choruses (WNO's huge resources in this area bigger than ever on this occasion). Conductor Lothar Koenigs gives a masterly interpretation of the score.

If the actions do not always speak louder than words, there are enough of these to convey the burden of the drama - essentially a struggle for power between rival factions that is eventually settled with the accession of ten-year-old Peter (eventually to be "the Great").

That this is a matter of jaw-jaw and war-war is eloquently expressed in Johan Engels's remarkable design. This is at once reminiscent, in its arrangements of desks punctuated by tunnelled stairs, both of an arena for political debate (say the UN headquarters) and one for fighting (say the Coliseum). In a stupendous start to the evening this is steadily illuminated (lighting: Fabrice Kebour) during the course of the lovely overture, thus giving up to our view a mass of sleeping figures - Red Square at sunrise. The end is mass suicide of the Old Believers, a religious group led by the charismatic Dosifei (Julian Close). The setting this time is the choral version of another 20th-century Russian giant, Stravinsky. It is moving and magnificent.