When the episode begins, a rich young man is kidnapped and his girlfriend is in on it...though no one knows it yet. Barnaby is called in on the case and ends up working with an old associate, Paul Craig. However, when Paul is making the money drop, it APPEARS as if Paul is murdered and the shake he dropped off the money to blows up. But this was orchestrated by Paul...as he killed the kidnapper and took the money...and exploded the cabin to obscure the identification of the body. Paul, apparently, planned the whole thing and didn't want to have to share the loot! Can Barnaby figure out what really happened and capture this murderous jerk-face? And, what about the woman...does the same go for Ellie?
This is a very clever episode...well written and interesting. I mention this because too many late season six and early season seven episodes were simply terrible...so terrible you have to wonder if they changed writers or just ran out of ideas. But here and in the prior episode, the show seems to be back on track.
By the way, although this was a very well made episode, you could not do this show today, as DNA testing is now common and simply wasn't possible back in 1978. This testing would establish exactly who really was killed in the explosion.
Also, one tiny part of the show did NOT ring true...Paul did NOT yet have his passport and had to get it before he and his lady could leave the country. Well, if you planned a crime this precisely, it's inconceivable that you wouldn't already have your passport.