I Start Counting is a 1970 British coming-of-age drama thriller film directed by David Greene and starring Jenny Agutter and Bryan Marshall.

While spying on George in the bathroom, Wynne notices he has several scratches on his back, and finds a jumper she made for him thrown in the rubbish, with blood on it; this leads her to suspect him of being the serial killer of several local teenage girls, who is still at large.

Later on, Wynne searches the back of George's van, hoping to find clues but is forced to stay inside and hide when he gets in and drives off.

He drives to a house and Wynne discovers that he is having an affair with a mentally unstable woman, whose blood was on the discarded jumper after she had slashed her wrists in a suicide attempt.

Greene overcomes most of the difficulties with some sensitive performances and an artfully smooth style that stitches together the psychological thriller, the whodunnit trail of hints and red herrings, and the fantasies and memories of Wynne's Catholic girlhood into a coherent and accomplished piece of film-making.

But for the most part, the rawness of the setting is not simply a symbol but an alive and active presence, the precarious, half-completed air of the place perfectly expressed in the muddy chaos of building sites adjoining the glitteringly modern church where Wynne goes to confess some of her problems.

Jenny Agutter's performance as Wynne is itself something of a remarkable balance, poised between naiveté and delicacy to suggest a perfectly natural innocent.