Lobo (15) <!-- none onestar twostar threestar fourstar fivestar -->

Based on a true story, this starts as a tight political thriller about a double agent, codenamed "Lobo" (wolf), who infiltrated the upper reaches of the ETA terrorist group during the mid-1970s. Lean, saturnine Eduardo Noriega plays Lobo as a deeply conflicted figure, a Basque who has helped ETA in minor ways but has wearied of their bombing campaigns and assassinations. Miguel Courtois' film plays on the loneliness of the double agent, who finds himself, as such risk-takers do, in a no-man's-land where neither side will protect him.

The screenplay loses clarity as it develops, dropping characters and then suddenly reintroducing them, and the perfidy of the authorities feels slightly glib. But the period - the last throes of Franco's dictatorship - and the backroom powerbroking of terrorism feel grittily realistic.