In an abandoned railway arch in the deep dark woods of West Yorkshire, two strangers set out to count bats. Biology professor Alison wants to track the endangered Daubenton’s bat, while young offender Tim wishes his probation worker had got him a work placement at Batley Shoezone instead. As they head into the cold, dripping arches, they find more than just a roosting site for Britain’s smallest flying mammal. Is there an unexpected guest in the arches?