Little dog Barney lives on a narrowboat with his owner, Jim. The pair are inseparable - until they get separated. Barney loves his life on the canals but the one thing he's frightened of is tunnels. So when Jim sets off into a tunnel without him, Barney is distraught. Luckily, another boat owner gives him a ride through the tunnel. When he gets to the other end Jim's boat is moored up - but Jim isn't on it! And in their efforts to be reunited, man and dog just keep missing each other until poor Barney is completely worn out. However, finally brave dog Barney has to overcome his fear and enter the nasty tunnel - alone.