The Bill:
Millennium. Sun Hill's new DS hits the ground running when she's plunged into a case of eco-terrorism after a supermarket finds someone has been injecting food products with mercury. This is a great episode that introduces the hugely significant character of DS Claire Stanton (Clara Salaman). At this stage, there is no hint that Claire is anything more than just a normal DS, though there is a wonderful moment at the end of the episode where she's on the phone to her "mother" telling her she'll be late. Given who "Mother" turns out to be next season, it's difficult not to suspect at least one person on The Bill staff was an Avengers fan...
