Dentist Frank Sangster puts his practice and his engagement to dental hygienist Jean under threat when he submits to the wiles of sexy Susan Ivey. Soon, painkillers go missing, bodies start to appear and Frank is wanted by everybody.
Novocaine is used by dentists to dull pain. Another favoured method is nitrous oxide - laughing gas. In watching a black comedy starring Steve Martin as a dentist - Little Shop Of Horrors, anyone? - you might hope for a movie deserving of the name Laughing Gas.
Sadly, writer-director David Atkins has loftier ambitions in mind (a Hitchcockian 'wrong man accused' thriller, for starters), and Martin's usual 'wild n' crazy guy' is kept on a very short leash. Which seems a waste of the man's prodigious comedy talents.
Pitch-black comedy is, of course, the hardest thing to get pitch-perfect. When it works, as it does in several excellent scenes here, you get the gut wrench of violence followed by the uneasy release of a good belly-laugh.
When it doesn't work, as happens in several poorly-paced sequences here, a movie can flop around between incompatible styles, ending up being neither one thing nor the other.
Really, it's a two-star movie with enough four-star moments to hint at how good it might have been.