A few thoughts:
-
Pretty sure Mark's watery suicide was via cliff jump. And the visions of older Danny in boat (and drowning himself), symbolic of Mark 'crossing' to the other side and joining him in death?
-
Feel so sorry for Chloe...imagine the guilt she'll feel about that last phone call. 
I initially thought perhaps she got help and Mark's rescued after all, but I think that would devalue the impact of such a moving end sequence.
-
Oh the irony: the only sensible, mature locals would seem to be teenage girls Leah and Chloe.
(For some reason, I'd assumed Leah was at Uni/ college...but she's another pupil at that school: might she have also become aware of amateur porn filming [or worse, been previously coerced/ blackmailed into taking part in them herself], not previously realising her own father's involved, but beginning to suspect now...
Perhaps Cocky Twine Boy gets Ice Cream Girlfriend to befriend and groom/ recruit local teens...reason for the I.O.U.s they both mentioned?).
- Could someone clarify if Miller actually saw a bit of Tom's phone porn (dinner table scene), or merely heard some of it, before she became so angry/ disgusted with him that (apparently) destroyed it and laptop (kitchen smashing scene)?
Seems bloody odd that she wouldn't first watch the entire thing, after hearing Dim Taxi Clive provided it... 
Surely, when mainstream, free, online porn's so widely accessible to all, including teen boys, it would ring major bells with her that it must have an illicit extra element, or why would Tom and DimTaxiClive's(Step)Son risk it?
*Still think Trish's filmed rape is as yet unseen, except between the perpetrator (s) and accomplice(s).
If next week's episode uncovers the porn ring, that's another irony that Miller'll then be deemed as closely related as DC Katie to someone suspected in a police investigation. Poor Miller.