`Rat in the Skull':a drama defining Ireland's struggle Rat in the Skull Play by Ron Hutchinson. Directed by Max Stafford-Clark.

``Rat in the Skull,'' at the Public Theater/Martinson Hall, seeks to define several centuries of Ireland's sectarian strife in terms of a brutal incident in a London police station. Whatever its accuracy or its limitations as instant history, the impact of the encounter is grimly harrowing in the performance tautly directed by Max Stafford-Clark. The fact that no violence occurs onstage endows Ron Hutchinson's savage drama with the austerity of Greek tragedy. The unequal contest observed by the audience is exclusively verbal; the onslaught of words proves the power of language in the hands of a writer of Mr. Hutchinson's mettle. The production by London's Royal Court Theatre is structurally stark. Designer Peter Hartwell's arrangement of abstract panels (lighted by Andy Phillips) suggests the impersonally threatening environs of any police station, in this case identified as Paddington Green in the British capital. In a silent prologue to the proceedings, a screen at the rear of the stage lights up with projected photo enlargements showing the battered face of Roche, the drama's terrorist suspect, arrested in connection with a bombing incident.

As the action commences, criminal investigator Harris (Phillip Jackson) is questioning young constable Naylor (Gerard Horan) about the circumstances under which Roche (Colum Convey) was beaten. It appears that the beating occurred while Naylor was fetching cups of tea for the suspect and interrogator Nelson (Brian Cox), a member of the Royal Ulster Constabulary (attached to the British police force).

The centerpiece of ``Rat in the Skull'' is Nelson's vicious verbal assault on Roche as the officer, a fellow Irishman, seeks to break the prisoner's resistance. In the course of this extraordinary volcano of words, Nelson contrasts himself with Roche -- the Protestant vs. the Roman Catholic, the ``farm boy'' vs. the ``city rat.'' Mr. Cox, who gave a remarkable performance earlier this season as the experimenting doctor-lover of ``Strange Interlude,'' reveals explosive histrionic and vocal resources as a fanatic in whom consuming hatred and a groping historical perspective are hopelessly entangled.

As Roche, Mr. Convey remains the silent victim of Nelson's harangue until taunted into his own vehement outburst. The ``rat in the skull'' -- the doubts Nelson claims already plague the young prisoner -- are insufficient to shake his own dangerous fanaticism. Messrs. Jackson and Horan are stalwartly ``regulation'' as the cynical investigator and the anxious tyro officer faced with the task of devising a report that will satisfy officialdom, create a minimum of fuss, and in any case force Nelson's resignation from the Royal Ulster Constabulary.

``Rat in the Skull'' seems unlikely to satisfy partisans on either side of this prolonged and bitter struggle, which may be the measure of its success. (Even with a lengthy glossary of terms and slang expressions, many spectators may find the heavily accented dialogue and its implications difficult to follow.) Mr. Hutchinson's final reflection on Ireland's ``troubles'' is ironic. The play closes with a serene, cycloramic view of the green, pleasant, and peaceful Irish countryside. The production, which continues the Public Theater's association with the Royal Court, is scheduled to run through June 23.