Wycliffe and his team investigate when 16 year-old Ruth Penrose is found in a gas-filled school lab by the school caretaker Alan Weir. She was locked in a cupboard and had a plastic bag over her head. Franks determines that death was due to suffocation rather than the gas. Ruth was at a school dance as was her twin sister Sheena and several of the girls had their eye on physics teacher Mick Brandon. It's soon apparent that Ruth and Sheena did not get along. Ruth, once the star of the school athletics team, had just been dropped by the coach for poor performance and was obviously anorexic. The caretaker's son Danny was one of Ruth's only friends and when the police find the key for the cupboard she was locked in in Danny's jacket, the police have a clear suspect. None of it sits well with Wycliffe who is trying to deal with his own rebellious son.
—garykmcd