Breathless and occasionally baffling, the plot of “Disclosure Day” is hard to summarise, but here goes: nuclear conflict looms in America.

Steven Spielberg’s “Disclosure Day” is one of those movies that sweeps you up from the start and rarely lets you down.

In Disclosure Day, O’Connor plays Daniel Kellner, a young cybersecurity pro who’s gone on the run for whistleblowing on, well, aliens.