The Comedy of Terrors (1964)
On the verge of bankruptcy, undertaker Vincent Price hits upon a novel method of drumming up business. Together with his cringing assistant Peter Lorre, Price sneaks into the homes of wealthy old men under cover of night and smothers the sleeping occupants to death--then collects a hefty commission when the victims' relatives come calling.
At home, Price is continually frustrated in his efforts to poison his senile father-in-law Boris Karloff, who owns the undertaking business. Meanwhile, Price's neglected wife Barbara Nichols takes quite a shine to the shy Lorre.
The homicidal undertaker's best-laid schemes go terribly agley when his latest customer, wealthy Basil Rathbone, doggedly refuses to stay dead. Joe E. Brown has a cameo as a cockney graveyard attendant.
