I’m still here, bitches, and I know everything.” With that one terrifying text, the lives of four 16 year-old American girls were sent tumbling into a nightmarish seven-year stretch of chaos, intimidation, manipulation, backstabbing, bullying, trauma, incarceration, addiction and near-death experiences at the hands of a ubiquitous, unseen tormentor known simply as A.

But now the endless ordeal of these brave, hapless young women comes to an end. Pretty Little Liars, the labyrinthine psychological thriller aimed at messing with the tousled heads of American female tweens, but avidly consumed by an audience that bridges both the generational and gender divide, is finally attempting to tie up its bizarre and intricately plotted storylines.

The feature-length final episode - showing on US TV tonight, and soon Netflix in the UK - will put paid to frenzied speculation about the identity/ies of A (in later seasons supplanted by the even more vicious, all-seeing Uber A and A.D.).