THEATRE / The Fringe: The devil and the sea of learning

The pursuit of knowledge is under fierce scrutiny in Greenwich. While Greenwich Studio's fine production of Erasmus Montanus - an 18th-century Danish comedy about a pompous student - continues, Greenwich Theatre has just opened a cracking staging of Marlowe's Doctor Faustus. The two plays offer a fascinating contrast: a sceptical comedy about a man who takes himself and his learning too seriously, and a tragedy about a man who has learnt all there is to know and takes none of it seriously. And both provide revealing portraits of the student life and preoccupations of their times.

Philip Franks sets his virtuoso production of Faustus amid the detritus of late-20th-century student life - Faustus dresses in the obligatory black, swigs from a milk bottle (you're sure he eats his beans straight from the tin as well) and lives in a dilapidated old room, complete with yellowing quilt and one-bar fire. The only drawback to this context is that some of the conditions of student life as drawn by Marlowe now jar: Faustus's youth and sparse surroundings make it hard to see him as a man who has spent years steeped in academic discipline, or to believe that he would have a servant (it might have been best to dispense with Wagner).

That aside, Franks uses his setting brilliantly to both contain and release the drama. All Faustus's tricks and journeys take place in this bare room (making you question whether they are, in fact, in his head), and Franks' inventive direction carries the fascination of magic into the stage effects. The horseplay in the Vatican is funny and not belaboured, while the Seven Deadly Sins, so often an embarrassment, are dealt with wonderfully, seeping out of appropriate bits of furniture like hallucinations - there's a sin in every corner of the house. It's a staging that conveys the horror of damnation not with crackling flames but by making Mephistophilis's words 'Why, this is Hell, nor am I out of it' ring coldly true.

Hugh Ross, as Mephistophilis, is excellent. Tall, suave and elegantly dressed, Ross has a still and powerful presence that can be truly chilling, and he manages to remain inscrutable while suggesting that he is deeply tormented. He is a good match for Jonathan Cullen's pale, febrile Faustus. Cullen hurtles around the stage, suggesting a restless intelligence and a reckless desire for experience, though he limits himself by beginning his delivery on the verge of hysteria and leaving himself little room to build towards a climax. But both cast and director bring to Marlowe's ambitious youthful work all the freshness and invention that you often find in a first-class student production, but sometimes miss in professional theatre.

The Magnificent Theatre Company unveils the work of the young Henry Fielding with its production of The Grub Street Opera (Lilian Baylis, EC1), tasting the stage for the first time 262 years after it was banned. The premiere doesn't reveal an early masterpiece, sadly - more of a sketch, written with the acerbity and energy of a young man.

The plot is slender in the extreme - a household love intrigue intended as a vehicle to satirise George II's monarchy and Walpole's government. It's hard to believe that it was deemed troublesome enough to muzzle, as the storyline seems cosy enough and the points of reference are lost on a modern audience, and it's perhaps a flaw in Ben Crocker's otherwise enjoyable production that he doesn't find a way of really driving the satire home. Instead, he opts for a fast and frothy pantomime staging, and is served by a versatile cast, who slip deftly in and out of the show's 60 airs (arranged by Jonathan Goldstein), and deliver ridiculous lines with relish, again lending the evening the spirit of a bitchy but harmless student revue.

'Doctor Faustus': 081-858 7755; 'The Grub Street Opera': 071-837 4104.