The Martin boys' elderly neighbor, Mr. Edwards has asked Joseph and Jonas Martin to feed his sheep. Of course, the boys are very excited. They invite their best friends Tanner and Simon Johnson to go along. This is the boys' chance to prove their trustworthiness to Mr. Edwards. But when Tanner's great idea turns into trouble the boys' day turns into another adventure. Mr. Edwards had ten sheep in his sheep pen, but now there are only nine. 'How can Mr. Edwards think them to be trustworthy when they lost his favorite sheep? The four boys must find the missing sheep!