A hit man is threatening one of Higgins' several female guests, which include Jessica Fletcher. Jessica and Magnum get off to a bad start with Thomas presenting himself as a professional who should handle everything. At the end of the episode, as shown in the intro to the MSW finale, Magnum shoots the hit man but the hit-man's gun somehow disappears and he's found to have been shot in the back. A police Lieutenant who doesn't like Magnum arrests him for murder. He winds up in jail. He doesn't like it but now Jessica is his best hope for getting out of jail.
MSW got the right to add the Magnum episode to their DVD as a bonus. But the Magnum people wanted the first episode to be a stand alone for syndication and later the DVD so a phony scene was shot with Magnum and Higgins talking about how Magnum has killed the bad guy and his employer has confessed and Jessica and the other ladies have returned to the mainland after realizing that Jessica was wrong in her theories of the case. Magnum is not in jail at all. This ending makes Jessica look like an idiot.
There ought to be agreement when cross-overs are done that the episode of the other series should be made available for syndication and DVDs of each show so viewers can see these episodes as they were intended to be seen, instead of creating a false ending that makes the star of the other show look bad.
Interestingly, the original Hawaii Five-0 had two episodes where McGarrett teams up with a middle-aged female mystery writer, (played by Mildred Natwick) to solve cases, (Frozen Assets 3/30/78, and The Spirit is Willie, 1/25/69). In one epsilon she's trying to find out how an old friend died and in another she's trying to find out what happened to her niece's husband. Either could easily be a Murder She Wrtoe- Hawaii Five crossover if the shows had been contemporary and both were better than this mish-mosh.