The Scooby-Doo! Show: The Tar Monster (1978)

 

A really fun episode. 

In this episode the gang go to visit their friend Dr. Brixton. Dr. Brixton is an archeologist who has just discovered a city that has been buried for thousands of years. However a fabled tar monster tries to scare everyone away from this spot. 

There is a whole lot to enjoy about this episode. An underground city is a wonderful location for a Scooby mystery and it is used to great effect here. It is a very atmospheric setting and has the right mix of creepiness and fun. Once again this setting allows for some truly wonderful background art that is a joy to look at and with this unique location truly makes this episode stand out. There is also so much detail and work put into these backgrounds that don't need to be there but enhance the episode a lot. While the tar monster may not be the most memorable Scooby-Doo villain, he has a good design that again combines creepy and fun pretty well. The humor in this episode is quite good. There are some really good gags here. Not only do Scooby and Shaggy get some good slapstick, but even a nameless spider gets a pretty good gag. 

The main problem with this episode is that there are too few suspects and because of this the mystery is often much too easy to solve. 

All in all a really good episode.