Max Minton is a meticulously careful safebreaker with a superstitious wife. At a house he is burgling he is disturbed by a pair of six-year-old twins, whose nurse has gone out. They tell him their birthday, and he guesses rightly that this will be the combination of the safe. So he gives them a present, which turns out not to be a good idea.
This Week, 13 October 1963.
Reprinted Argosy January 1964.