Marnie was a barmaid at Bar 103 in Hurley Road, Manchester. In August 2017, Michelle Connor was having a drink alone there when she had her drink spiked and awoke several hours later bound and gagged in the boot of what turned out to be her own car. Released by a passing woman, she told the police that she suspected that the person who had drugged her had been Rich Collis, a dealer who some years before had been the supplier of her now-partner Robert Preston. Desperate for cash, Rich had been blackmailing Robert with the threat of exposing him to Michelle, but he confessed his past misdeeds himself and he and Michelle set him up in order that the police caught him.
Robert was jailed for assaulting Rich in anger but Michelle soon grew suspicious of Will Chatterton, a teenage love who she had recently made contact with again who, unbeknownst to her, had become infatuated and was stalking her. She discovered photographs that he had surreptitiously taken of her and realising who the true culprit was, she went back to Bar 103 where she spoke to two of the bar staff, Josh, an old friend of hers, and Marnie. She recognised a photo of Will that Michelle showed her, saying he was "well fit" and recalled that it was odd the way that he came in, hung around and then hurried out without ordering a drink. Her testimony gave Michelle enough to investigate Will further with the intention of reporting him to the police.