Strange Intruder (1956)

Synopsis
In one of his last appearances in a Hollywood production, Edmund Purdom plays Korean war veteran Paul Quentin. Keeping his promise to his dead war buddy Adrian (Donald Murphy), Quentin arrives at the doorstep of his Adrian's widow Alice (Ida Lupino). Alice and her children welcome Quentin with open arms, little suspecting that his mission includes killing the children as retribution for Alice's alleged infidelities. Ultimately, Quentin grows too fond of the kids to carry out his bloody task, but there's still slimy blackmailer Howard (Jacques Bergerac) to contend with. Strange Intruder is based on a novel by Helen Fowler. ~ Hal Erickson, All Movie Guide