Over nine days, artists selected by Art in Situ and funded by The Arts Council, responded in their own way to the medieval tower of Crest, in South East France, a prison for 200 years.

Helen Ganly was struck by the similarity between the castle and St George's Tower, in Oxford, both built during the time of William the Conqueror, both windowless stone keeps housing prisoners. In France, she worked in a cell that held 56 men. One of her pictures shows a letter to the governor begging for light - a moving testament. Photographing 18 of her co-artists against the harsh walls, she captures each nameless 'mug shot' drained of emotion behind white cardboard bars. Later she focused on the imprisoned Empress Matilda, who escaped in 1142 from Oxford Castle, crossed the frozen Thames and eventually reached France. Ganly's beautiful workbook is a testament to her fine artistry.

Mohamed Bushara, a member of the Oxford Printmakers Co-operative, admits often starting "his work from nowhere". In Crest, he discovered inspiration and exciting materials to hand. Working with a French artist in her studio, he found neither a printing press nor etching paper. Instead, using nitric acid and black ink, he took the zinc plates as objects rather than a printing surface. Affected by the graffiti of the prisoners, he also experimented with collage, using magazines and newspapers. His work is suggestive, scratching below the surface to reveal a shimmering play of light and dark expressing the hopelessness of imprisonment - a far cry from the freedom of light-hearted tourists exploring the French medieval tower.

La Tour de Crest moved Madi Acharya-Baskerville with its rough, rich texture and its graffiti. In Temple she takes recycled pieces of wood to explore childhood memories and Indian culture. The notions of entrapment and escape are suggested by her own graffiti: the elegant knight leaving the tower, the anger of the goddess Kali, the pink flower found neglected on the roadside, the narrow window (pictured) suggesting a slit in the tower. Painted on blocks of wood Freebird tells the story of birds - one caged in the city, the other free in the forest - while the musical soundtrack combines mechanical and natural songs: a lovely installation to hang in a child's room.

The exhibition is at Oxfordshire Museum, Woodstock, until March 30.f=Swis721 Blk BT Jan Lee