Adventure at the Center of the Earth

It's a bit difficult for me to write a completely accurate review of this film, as no dubbed or subtitled copy exists, and my Spanish is not good enough for me to really follow the dialog. Luckily, the plot is simple enough for a non-Spanish speaker to get the gist of it without understanding the (probably silly) interactions between the characters. The plot concerns a group of scientists who have an interest in human evolution journey beneath the earth through a series of picturesque caverns where they endure hardships, betrayal by one of the expedition members, and some deadly encounters with humanoid monsters, some of them sporting big bat wings on their shoulders. There's also a giant spider. The monster make-up and effects are, on the whole, excellent.