A Piece of the Moon Is Missing — James L. Johnson

This new Code Name Sebastian finds that good man of God who does "not faint in the day of adversity" sent up to the North Pole where a Professor Thorsen, desperate and dangerous after his -- and Sebastian's -- failure with his son, is supposedly carrying a highly lethal moon rock which can blow the world up. Sebastian is to kill him. Before he breaks that commandment, he staggers across the ice with an Eskimo who falls through it after drinking up the primus fuel, sees the dogs die off, and gratefully meets up with the girl who helped him in the Negev. Apparently Sebastian is "fearfully and wonderfully made". . .to last. -- Kirkus Reviews