In The Masters of Silence (1965), Engineer Milland has been summoned to a secret lab by Professor Watson, but when he arrives, Watson has just been murdered by his wife, Valerie, during what is said to be a fit of madness. Valerie had tested a machine to explore the Inner Mind invented by her husband. Milland volunteers to go into her mind-but, in so doing, may unleash creatures of darkness upon the Earth...
In They Came from the Dark (1967), Ashby, just released from prison, finds himself hired on a ghost ship that travels through time, picking up derelicts like him. He eventually ends up in a mysterious Antarctic valley, which exists outside of time, inhabited by monstrous alien parasites intent on spreading upon the rest of the Earth like an unstoppable disease.
Two classics of French sf/horror by an acknowledged master of the genre, with an introduction by Stephen R. Bissette.