I think some people are making it far more complicated than its going to be. 
Ian and Vincent are not related, they just shared photos.
I think the mayor (George) is also part of the ring which is why Ian gets away with stuff/gets favours.
Policeman in prison was set up.
Nothing with James except he reminds Emily of Ollie and she has used him has some sort of replacement to cope.
Mark, hmm dodgy possibly but I don't think he had anything to do with it.
The only thing Tony and his FIL did has already been revealed, FIL helped cover up Tony beating up care home guy, who Emily did have an affair with (I think). Although Mark does seem to know him and I'm sure it was around the time Emily would have been pregnant but I don't think they would have a series where Tony goes through all this only to find out Ollie want his.
I don't think Baptiste's DD has anything to do with it at all and that's just something there to show another side to his life.
I thought Monique was just random but if she pops up again then maybe not.
Mollie is dead, Ian killed her.
Mary went mad because she knew what Man was and what he did to their daughter.
Vincent was seeing Mary as the old friend in order to tell where what I an really was.
Ollie was taken by trafficking/paedophile ring. It was not planned but crime of opportunity. Cleaning guy involved because he knew that house was empty. I don't think they will find him alive unfortunately but there maybe some sort of closure for Tony.
Mark and Emily will split up.
Journalist will get what's coming to him.