Martyrs to hypochondria and general seediness, J. and his friends George and Harris decide that a jaunt up the Thames would suit them to a'T'. But when they set off, they can hardly predict the troubles that lie ahead with tow-ropes, unreliable weather-forecasts and tins of pineapple chunks - not to mention the devastation left in the wake of J.'s small fox-terrier Montmorency.