Rich Cassie Denham (Sarah Padden) is a more than an eccentric millionairess. After her scheming relatives unsuccessfully try to have her committed to an institution, Aunt Cassie invites them for a weekend in the country to "study them like rats" and see to whom she will bequeath her fortune. At the stroke of midnight a murderer strikes, and in the suspense-filled hours just before dawn, her greedy, corrupt relatives are dispatched one by one. Having received a tip, ace reporter Bob White (Wallace Ford) and his girl Friday (Marian Marsh) arrive on the scene to investigate. Thrown into the intrigue, it becomes clear that they are not only suspects but possible victims as well.
Evocatively shot by cameraman Marcel Le Picard, filled with sharp, snappy banter and set in a mansion complete with secret passages and trap doors, Murder By Invitation is a superbly inviting whodunit in the Agatha Christie tradition.