The Great Steamer

S1, E4: After Rat's place is shaken by the passing of a great steamer, he and Mole hear the calls of the riverbank youngsters, who have lost their friend Billy (a fieldmouse) in the commotion. A desperate search for ensues, and he is found clinging perilously close to the weir. Rat and Mole stage a brave rescue, and bring the youngsters back to the rat's to dry off and have a hot drink. Rat admonishes the youngsters for playing dangerously on the river, before entertaining them with a rendition of "We'll Go Boating".