While they were wandering through the fog, trying to find Martin again, someone came along and stole something from Anthony. It was obviously unaware that he had an entire group with him, because he ran right towards Matt, Josh, and Xeno. Josh used Water Gun on the thief, while Matt put up a Reflect, just in case they tried to attack.
"Try to surround him." Matt said.
Matt tried to position himself in a way that the thief wouldn't be able to get away. Hopefully, with the help of the others, he would be able to block the thief's escape route.