"Dr. Jekyll and Mr. Duke" is the third episode of the seventh season of The Dukes Of Hazzard.
Bo, Luke, and Daisy are on their way to an old fashioned hay ride. Meanwhile, a truck carrying an experimental genetic drug accidentally drops a vial of it into the Hazzard pond. Shortly after, the Dukes must stop at the pond to get water for the General Lee’s radiator, since it has overheated. While filling a jug of water from the lake, Luke also takes a small drink. He does not realise that he is drinking water that has been contaminated by the genetic drug. Luke begins to experience a severe personality change. He becomes obnoxious, and he begins to turn on Bo. When they get to the hay ride, Luke insults Enos and says that he now sees that Hazzard is just a joke of a town. When all the Dukes are back at the farm, Luke continues to insult his family. He forgoes the ceremony of saying grace and he insults Uncle Jesse’s cooking. For Bo, this is the last straw, and he wants to have it out with Luke. Jesse asks Bo to hold back. Luke takes off in the General. Out of respect for Jesse’s wishes, Bo agrees to go look for the dramatically changed Luke. Luke, who is now under the full influence of the drug, goes on a rampage, even running Bo off the road. Luke is observed by Hurley (Alan Autry) and Ben (Greg Finley), two men who are planning to rob the Hazzard Bank, and they are looking for a good getaway driver. Luke, in his current frame of mind, agrees to help them, for a cut of the money. Soon, Boss Hogg becomes aware of Hurley and Ben’s plans to rob his bank, and begins to devise his own plan to catch Hurley, Ben, and especially Luke in the act. Meanwhile, the remaining Dukes have discovered the empty genetic drug vial at the lake, and have gone to the research company in Atlanta to find out more information, in hopes of saving Luke from its effects. Dr. Debbie Davis (Lori Hallier) tells them that that the drug will not wear off until 11:00 AM the following morning. The Dukes hurry back to Hazzard to try to prevent Luke from getting himself into trouble. However, they arrive too late. Luke has already done the robbery with Hurley and Ben, and he has been videotaped by Boss’ surveillance cameras. It is up to Uncle Jesse and Daisy to catch up to Rosco and get the tape from him before he delivers it to the authorities. Rosco is unwilling to listen to their story, but Rosco's dog Flash chews the tape up. Bo and Enos find Hurley and Ben. Bo has it out with Luke. During the fight, the drug wears off, and Luke is his old self again. Luke apologizes to everyone that he had insulted while he was under the influence of the drug, and everyone is forgiving.
- Alan Autry as Hurley
- Lori Hallier as Dr. Debbie Davis
- Greg Finley as Ben
- Ben Slack as Mr. Adams
- James Bradford as Toby
- Richard Johnson as Zeb
- Parley Baer as Doc Appleby
- As of this episode, Bo Duke is the only one of the main Duke Family not to have fired a gun
- Daisy Duke had first fired a gun onscreen in Officer Daisy Duke and Jesse Duke has fired his shot gun a number of times. Luke had previously handled guns in the Marines, however has not fired one since he returned to Hazzard.