The plot & teleplay take what is otherwise an average episode an elevate it to something a tad more. Dialogue is average at best, while most scenes are limited by the lack of any real action or intrigue. Even the voodoo link is tenuous at best and is quickly discarded as the real reason behind the murder becomes apparent.
This is strictly a follow-the-breadcrumbs story, when practically none of the clues, events or scenes attempt to distract us from the core plot. Action on the ground is limited.
It is only a few degrees above being a filler episode. Perhaps though the most important events in this episode are the ones affecting Cobbs and his attempt to help out the friend in prison he had to kill in order to survice the flood.
Definitely not as good as the first three episodes.