Even Yuppies Die — Marian Babson

Trixie Dolan and Evangeline Sinclair, Babson's feisty elderly heroines, are back, just as bickering, inquisitive, and delightful as ever. The two former film stars are at leisure (temporarily, of course) but they have, again of course, expectations of juicy parts in a movie in the near future.
Meanwhile, circumstances force a move to a penthouse suite in an only partially remodeled London warehouse. Currently the quarters are pretty primitive, but the two actresses cope bravely, not even minding the dangerous door in the kitchen that opens onto an unguarded three-story drop. They are rather pleased by it, in fact, since conversations from the strange and contentious assortment of tenants who occupy the rest of the building come right up to the ladies' eager ears and they become gleefully immersed in the troubles of their neighbors.
Curiosity changes to unease, however, the more they learn. When a young woman's body is pulled out of the river, their suspicious are confirmed, and they are plunged into the center of a perilous series of events.