This is an average thriller with good performances all-round. Trevor Howard is excellent as an ex-spy, David Somers, taking a break to work on cataloguing butterflies in the Fentons' country house. There he meets their highly-strung niece, Sophie. The film plot in some ways resembles the plot of 'Gaslight' when we see her strict aunt Jess is intent on convincing Sophie that she is losing her memory.
When the police suspect Sophie of murder, she goes on the run with Somers. This gives us an excuse to take a trip around early 1950's Britain. Somers makes full use of the contacts he made during his previous spying experience.
After a short stay in Newcastle the couple travel on to the Lake District and we have an opportunity to indulge in the scenic beauty of Ullswater, Patterdale as well as the waterfall at Sourmilk Gill.
In contrast to the countryside scenes, the denouement takes place in Liverpool. There is a small final twist, but anyone watching carefully will notice that this twist had been hinted at some time beforehand. Nevertheless the film is enjoyable and doesn't put too many demands upon the viewer. 6/10.