Frustrated at recycling stock sounds, the director of "Co-ed Frenzy" sends Jack out to try and record some more environmental sounds.
While recording in a park late in the evening he witnesses an incident where a car suffers the titular 'blow out' and goes over a bridge into an ornamental lake.
Jack dives into the lake and rescues a young woman, Sally (Nancy Allen) from the rapidly sinking car but fails to rescue the driver.
Later in hospital he finds out the driver was a prominent Congressman tipped for a run at the Presidency. The Congressman's aide persuades a reluctant Jack to pretend that Sally was never there in order to prevent a scandal. Reviewing the tape he had running when the car went over the bridge, Jack concludes something more sinister happened and tries to get people to listen.
No good will come of this.
Brian De Palma's 80s conspiracy thriller has aged very well.
Many such things require quite a suspension of disbelief, a hugely competent shadowy adversary and often coincidental happenings but this is all logical and believable.
There are multiple layers and very little in the way of macho action: Jack is trying to deal with a cover up using the skills and contacts he has. Sally while shown as a slightly daffy occasional sex worker low on agency is believable in that situation and while tragic isn't there just to be rescued.
It goes slightly unexpected places and is one of the best things of this ilk I've seen for a while 9/10.