Charlene Kozlowski, an out-of-town client, engages Private Investigator Frank Johnson to track down her missing father, Mule Kozlowski. She last heard from him while he was in Frank's local area. Frank doesn't consider missing person cases as his specialty since he hasn't investigated one recently. He launches his search with his agency partner, Gerald Peyton, for a lead on Mule's present whereabouts. The clues are tedious to come by, and progress is direly slow, despite Frank's hard-nosed tenacity.
Things take a sinister turn when they discover Mule was a courier ("mule") for the Mexican drug cartels. Frank understandably avoids getting too close to investigating the brutal cartel's narco crimes. Meanwhile, he performs a background check on an unsavory music teacher; advises his suicidal friend who moved to Florida; and runs surveillance on an unusual infidelity case. He never loses his wry humor and cool nerve when things heat up and climax with a life-changing result.
