Fly-tippers often work in the dead of night dumping rubbish on other people's land, where it is expensive to move and can even be life-threatening. An emergency team is called out of Birmingham New Street station to clear a giant fly-tip which is about to fall onto the track. We've all heard of leaves on the line, even a single crisp packet discarded by a careless passenger can stop a set of railway points working, causing track closures and delay. In Wellingborough, Northamptonshire, an environment officer sets off on the trail of serious fly-tippers. He's got some evidence and wants to track them down - but will he find the criminals and bring them to book? Meanwhile Adrian Ablett has started a one-man campaign to rid Leicester of littered drinks cans. He cycles round picking them up from the street and hands them in to be recycled. He started with a bin, progressed to a bike, and now has an electric tricycle funded by supporters. He has collected more than 142,000 cans. Hay-on-Wye in Wales is the location for a psychological experiment to get litterers to use litter bins. Like town centres up and down the country, Hay had litter on the ground around perfectly good bins but the mayor of Hay thinks enforcement won't work in this bookish town. So psychologist Ceri Davies is conducting a trial: would bright green footprints painted on the ground 'nudge' residents and visitors to do the right thing and bin their litter?