During a particularly intense Florida heatwave, inept local lawyer Ned Racine (William Hurt) begins an affair with Matty (Kathleen Turner), the wife of wealthy businessman, Edmund Walker (Richard Crenna). One night Ned arrives at the Walker mansion and playfully propositions a woman who he mistakenly thinks is Matty. The woman is Mary Ann Simpson (Kim Zimmer), Matty's visiting high school friend. Soon after, Matty tells Ned she wants to divorce Edmund, but their prenuptial agreement would leave her with little money. Eventually Ned suggests murdering Edmund so Matty can inherit his wealth. He consults a shady former client, Teddy Lewis (Mickey Rourke), an expert on incendiary devices, who supplies Ned with a bomb while strongly encouraging him to abandon whatever he is scheming.