Like so many who fall beneath the boot heels of its relentless onward march, Cerberus didn't see progress coming. Having spent their entire life, since time immemorial, guarding the gates of Death's Netherworld, the last thing they expected was to be replaced by  new hi-tech security system. But replaced they are.

Exiled to an animal shelter, a despondent Cerberus struggles to adapt. They are an old dog and they don't easily learn new tricks. Until Amy, a young girl with Down Syndrome volunteering at the shelter, takes a shine to them. But can she get through to them before progress once again overtakes them and a relentless threat to humanity is unleashed?