Miranda meets Brendan, a charming bloke, beds him in an instant, and then is amazed to find out he's a cad! Excuse me dear, in this day and age that's self destructive. He gets royally ticked off when she dumps him and gets his own back by dating her sister and ingratiating himself with her clueless family.
There is her brother, mentally ill, and a certain foil for Brendan's evil influence. He mugs Miranda's next love, apparently at Brendan's urging, who then departs the scene when he thinks Miranda is too obsessed with Brendan's manipulations. Miranda discovers Brendan's past is full of "crazy" behavior and dumps it all out at a family gathering, but no-one believes her, the silly saps all go against her "evidence". Why? Because Brendan has a bombshell of his own to drop. Miranda slept with her sister's former boyfriend back in God knows when! How does he know: he read it in her diary.
Does anyone, including Miranda, point out that her "evidence" come from a source that can be contacted and verified whereas his "evidence" comes from underhandedness. No! Mom and Dad go with Brendan's obvious "cattiness", because that drives on the drama! Then her brother kills himself, and we are left to believe Brendan had something to do with it, but he's so cloyingly self effacing at the funeral that everyone - except Miranda - falls for it.
When Brendan dumps the sister and marries Miranda's best friend, are the parents chagrined by their disloyalty? There is no sign of it. The sister even blames Miranda for it! What did Miranda do to deserve such a clueless and uncharitable lot? Then Brendan's new bride shows up dead in her bath tub. The police, evidently without any access to CSI technology, declare it as an accident! Another plot device to drive on the drama: make the cops look like idiots! It goes on and on, with poor old stupid Miranda being out foxed at every turn by this evil SOB! She's so stupid that when he manages to convince a Judge (who also does not seem to have access to evidentiary procedures) that she is a menace, and has a restraining order placed against her, she goes running off to his home when his latest bride calls her! Hey, it's effective to most of the female audience! By now they're so wrapped up with him getting his come uppance, that they don't care if the usual detective work goes missing! In the end she gets her revenge and poor old Brendan is hauled off to Jail for something he is innocent of, namely her murder. She lets her family believe she's been murdered, until Brendan is safely ensconced in Jail and then shows up to meet them at the airport in Australia! The dim witted couple are so pleased to see her, and evidently so pleased that Brendan is in Jail on trumped up charges, that they all live happily ever after! The plot is exasperating yet enthrallingly bad, It's enthralling if you accept that everyone has to ignore the obvious, and that is: The authorities are all stupid and incompetent! The main protagonist has a past, as our heroine uncovers. Do the police check it out: NO! Does the Judge check it out? NO! Do her parents check it out: NO! Does her sister: NO! It's all a typical BBC production, predicated on the audience being interested enough in the unfolding drama, that they accept that this guy is going to continue to fool everybody, so that our heroine has to take justice into her own hands. Roll over Agatha!