Mike and Greg sent to work on the Mercury. One day, their robot called Speedy was missing from the station while it was sending to do its routine work . Donovan and Powell decided to use old robots from the first expedition to find Speedy. It is well known that traveling along the way on the Mercury is dangerous. Nevertheless, they traveled through tunnels of the mining station. At the time, Speedy was at the selenium pool. The reason why Speedy did not come back to the station was because he had been confusing with the three laws of robot . By the second law, Speedy has to obey the human’s orders . In the moment, he was ordered to bring back selenium. On the other hand, there was some gas above the selenium pool that coming out from underground. Therefore, the reaction between the gas and the iron parts of Speedy’s body might cause him to explode. Thus, he needed to protect himself. Mike and Greg concluded that the second law drove him to the pooland the third drove him back. It was being like that as a loop. Mike and Greg agreed to fix the problem by giving Speedy new orders. Powell went after Speedy who was repeated his circle direction around the pool. Powell was in danger because the heat from the sun was burning him and there was not enough oxygen . Finally, Speedy rescued Powell with no excuse by canceling all original orders.