With many elements purloined from Black Book and Suite Française, this is perfectly watchable hokum despite a
wholly implausible plot which makes Allied look like a documentary by comparison.
All three of those films are much better!
.. and a typical annoyance has the actors talking to each other in vaguely foreign accents which doesn't help credibility.
It does however benefit from yet another tremendous late career performance by Christopher Plummer, excellent support from Janet McTeer and Ben Daniels, a cameo from Eddie Marsan as Himmler and of course the lovely Lily James in the lead.