It's a European thriller from the 60's-70's where a sorcerer prepares a note with ancient runes on it, which whoever receives it - dies a short time afterwards, unless he gives it to someone else (who again, dies soon unless... and so on) There's a (married?) couple that somehow learns about this, maybe they try to stop him, but anyway he fools them into receiving the note. They ultimately manage to give it back to him (not before the note tries to escape from them) right before he boards a plane and the plane consequently crashes.
This sounds like M.R. James' story Casting the Runes, which was adapted several times in TV and film, all containing the basic plot: An evil cultist named Karswell is killing people with a cursed parchment written in ancient runes; he's then fooled into taking the parchment himself and dies. It was the plot of Jacques Tourneur's 1957 film Night of the Demon (AKA Curse of the Demon) and a 1968 episode of Mystery and Imagination.
However, I think the version you're after is the 1979 ITV Playhouse episode (called Casting the Runes) because Karswell dies in a plane crash there (he's killed by a demon on a train in Tourneur's film and in a park in Mystery and Imagination). The heroes investigating the mystery are a man and a woman (they're not married, though); they trick Karswell into taking the cursed note right before he boards a flight by hiding it in the ticket. Here's the trailer: