There was an earthquake in the American smalltown of Sutcliffe recently: it shook up the residents a little, did some damage but not much, so nobody thought it was anything worth worrying over. But something else was damaged too, something in the nearby forest, in a spot cordoned off behind a security fence. Could this be something to do with the telephone call ballerina Jennifer (Meg Tilly) receives when in the big city from her mother? The woman is obviously distressed and calls her all sorts of names before attempting suicide by gunshot - Jennifer must now return to Sutcliffe to find out what is going on.
The film which springs to mind when watching Impulse is George A. Romero's The Crazies, for it used the same kind of plot to relay its chills, except here while things did get violent there was a more subtle approach as if the creators wished to unsettle and unnerve the audience by degrees rather than outright terrify them. So you would not so much be on the edge of your seat watching this and more intrigued as to where it was heading, though some would complain it took that bit too long to reach its destination which even then was largely inconclusive, not so much building to a shattering climax as leaving it up to us to decide what Jennifer will do.
Before that, we had to contemplate what was up with those townspeople as they went loopy, and that was not quite as obliquely presented as some would have you believe, as once we see the large concrete block with a crack in it we can surmise that something is leaking into the town's water supply. Except it's not actually the water that's the problem, and you can cotton onto that if you're paying attention in the earlier stages. Jennifer takes her doctor boyfriend Stuart (Tim Matheson) with her when she travels back home for support, but he's not sure he's welcome in the family - or anywhere else as the locals do demonstrate a strange reaction to him and his girlfriend.
After all, he can sort of understand why Jennifer's brother Eddie (Bill Paxton) might be unwilling to warm to him, but why would a complete stranger piss on his car while he was waiting in the high street? That's not all that's odd, and these events accumulate into a series of increasingly lunatic, then murderous behaviour, all from people who had been otherwise polite, peace loving and easygoing up till the point of the earthquake. That feeling that everyone except you has started to become unfriendly and downright hostile after a while is a disquieting one, the thought that it's not you who have gone mad but everyone else instead, and that's what director Graham Baker counted on would keep the audience sufficiently gripped.
Yet the leisurely pace would appear to work against that kind of suspense, with setpieces rather blankly nasty rather than over the top and screaming pitch, which other, more sensational efforts might have wasted no time to reaching. Nevertheless, there was a darkly comic tone to the mayhem if your sense of humour was sufficiently tickled by the out of the ordinary manner in which the violence mounts. This is so inscrutable that perhaps for all you know it was meant to be funny, but scenes of the kindly doctor (Hume Cronyn) irritatedly suffocating Jennifer's mother on life support just for kicks, or the Sheriff (Claude Earl Jones) taking potshots with an assault rifle at the teen delinquent spoke to a bleak sense of humanity rather than laughing it up as if this were the chemical spill version of the seventies comedy Cold Turkey. Neatly performed, with Tilly convincingly vulnerable as the sole person not to be affected (or is she?), Impulse was not a major work, but had something about it which kept you watching. Music by Paul Chihara.