In an isolated motel somewhere south of Memphis, FBI bookkeeper Simon Welch takes on his first assignment as a field agent: surveillance on the notorious thief Michael Casiello and his moll Samantha. However, after weeks of spying on the lovebirds, Simon finds himself falling for the dame. When a chance meeting sparks a torrid affair, she convinces the honest lawman plot the untimely murder of her criminal mate. But the question soon looms in Simon's mind: how long before she takes another lover and how long before they plot his own murder?