His Wife's Friend is a lost[1] 1919 American silent mystery film directed by Joe De Grasse and written by John Burland Harris-Burland and R. Cecil Smith.

[2][3] As described in a film magazine,[4] Lady Marion Grimwood (Dalton) finds little congeniality in her union with Sir Robert Grimwood (Cook) and welcomes the innocent attentions of John Heritage (Mortimer) when he shows an interest in her.

While she ponders over this, unwilling to believe in its entirety, she is attacked by Sir Waiverly (Neill), whose attempt to kill her is blocked.

It is then discovered that a Chinese man, Ling Foo, possesses a poison that paralyzes will power.

With this last obstacle removed, Lady Marion and John look forward to a life of happiness.