In an attempt to return Ian and Barbara to the twentieth century, the Doctor tries an unorthodox new technique. It causes the TARDIS doors to open in mid-flight, which sets alarms ringing inside the craft. The time travelers arrive on Earth only to discover that they have been drastically reduced in size. They are now tiny people in a world of giant objects. The TARDIS has materialized between the cracks in a garden patio. The garden is teeming with giant worms, ants and cats - all deadly hazards for the miniature time travelers.