in the --- place

in the --- place  {adv. phr.}

As the (first or second or third, etc.) thing in order or importance; first, second, or third, etc. — Used with "first", "second", "third", and other ordinal numbers.

No, you cannot go swimming. In the first place, the water is too cold; and, in the second place, there is not time enough before dinner.

Stealing is wrong, in the first place, because it hurts others, and, in the second place, because it hurts you.

Compare: FOR ONE THING.