Confined to his basket in the porch following the unfortunate incident with Dad's slipper, Ernie is, quite literally, in the dog house. And when his owner, a girl named Martha, accidentally throws his favourite toy bone into next door's garden, things go from bad to worse! Aided by his friend, a mangy but extremely clever mouse named Montgomery, Ernie sets out on a desperate mission to rescue his bone. Little does he know that the garden next door is patrolled by a fierce and bad-tempered bulldog named Max who has already claimed it as his own, and who will not take kindly to anyone he catches trying to steal it...