First in a long and extremely popular series, the main sleuth is actually Lt. Weigand of the NYC police - this is a cosy police procedural, with some nice bits of The Norths - who find the body - even though most people only remember them. In this first novel they do only a little sleuthing, and the focus is on police procedure.
from the back cover of The Thorndike Edition: "THE NORTHS MEET MURDER in the top-floor studio of the old house in which they live. Long left vacant, Mrs. North decides it is just the place for a party and takes her hsband up to check it out. They open a door - and find a murdered man in the bathtub! With no clue, not even the identity of the corpse, nothing to start from but the Norths and thei black cat Pete, Detective Weigand begins spinning his web and gathereing into it the most amazing conglomeration of information. With the aid of Mrs. North's "hunches" he carries through to a brilliant, entertaining and fascinating conclusion."
What do You think about The Norths Meet Murder (1994)?