Sponsored by The Sammarinese Swallow, the best new crime drama, starring David Walliams, on The Crime Network.

This week's episode is very special indeed: it's a video podcast! Except you can't see this video here so head over to YouTube (soon) instead.

The boys discuss electrolytes in A-Z of Brains, and Barrett, once again, isn't fond of having so many chemicals in his body. John tries to reassure him, but who knows if it's worked or not. Then Barrett helps little kiddy Connor, who wants to be a firefighter, because he has such a love of fires. Needless to say, this won't be plain sailing. Then it's a Featured Problem, where Kate, a scientist's assistant, is not so sure if she wants to help with his latest dubious invention.