Every letter of the group FROG is replaced by the letter standing three places ahead of it in the English alphabet, and the four letters so obtained are then written down in reverse order. What is the final group of letters?

F at place 6 becomes I, R at 18 becomes U, O at 15 becomes R, and G at 7 becomes J, giving IURJ; reversed, that is JRUI. Stopping after the move ahead, without reversing, gives IURJ. Moving each letter three places back instead gives COLD, and reversing that gives DLOC.