Xue's strengths as a filmmaker may lie more in fluffy comedy than in carefully calibrated tension.

The result is all over the map, in every sense. But despite the stilted acting and artless expository dialogue, the unpredictable shifts of gear hold attention over most if not all of the lengthy running time.

The Whistleblower starts to feel needlessly woolly by the end, and British viewers may find one particular script quirk impassable.

Tang Wei (Lust, Caution) and Lei Jiayin (The Wandering Earth) star in this old-fashioned action-thriller come romance