A Nazi-hunting thriller deepens into a meditation on conscience in The Debt. We watch the same characters over two time periods. In 1997, Mossad agent Rachel Singer (Helen Mirren) is being honored for her heroism 30 years prior for killing Vogel (Jesper Christensen), the notorious surgeon of Birkenau. But did she? Stephan (Tom Wilkinson), Rachel’s ex-husband and partner in the mission, informs her that David (Ciarán Hinds), the third member of the team, has just killed himself. And so director John Madden (Shakespeare in Love) flashes back to the past to show us what really transpired when young Rachel (Jessica Chastain), Stephan (Marton Csokas) and David (Sam Worthington) captured Vogel in East Berlin. These scenes exude shivering suspense as well as sexual tension. Chastain (a nifty match-up with Mirren) is a live wire, and her scenes with Csokas and Worthington have a spark the later scenes lack. No matter. The Debt holds you in its grip.