The Tweenies are fascinated by whistling but are frustrated by their inability to actually do it - until Max brings them a bag of whistles. They make so much noise that they're told to play something more quiet. Meanwhile, Doodles is behaving very strangely. Bella meets some birds in the garden who show her how to whistle like them. Judy reads the Tweenies a story, Max reappears and the mystery of Doodles' behaviour is explained.