Well, an interesting development in last night's (Aust) episode (Thurs Aug 10) which may cast some doubt on the theory/rumour that Charlotte murders Denny, so :
SPOILER ALERT!!!!
Denny is introduced to Roo's new boyfriend, Dr James for the first time & she thinks that she has met him or knows him from somewhere before. He says they haven't met & he probably just has "one of those faces". Denny ponders it for a while & when she fronts him again, saying she is sure she knows him & starts asking him questions about where they could have met in the City, he shuts her down by quite sternly asking her to save them the aggravation by dropping it. Denny leaves (a bit miffed), & James then lies to Roo when she asks him what his "discussion" with Denny was about. He also gives Denny a "worried" type of look later on when she comes back to the Diner (but is only looking for Ash).
Is there something sinister in James' past that he thinks Denny might expose if she can remember where she knows him from? Is it enough for him to want to kill her so he won't be found out? Or maybe this is just a red herring, & whatever Denny might know about him is only a relatively smaller thing - but still might have implications for his relationship with Roo?? The plot thickens!