How is “if ever there was” used?

In The Letter (1940), one line is: “If ever there was a simple, uncomplicated case, it's this one.”

Which movie is “if ever there was” from?

The clip at the top of this page is from The Letter (1940).

If ever there was a simple, uncomplicated case, it's this one.

5 作品で登場 · 1 本目

used to emphasize that sth is certainly true

くだけた · 5 本の映画に登場

オックスフォード映画の 100%
used to emphasize that sth is certainly true
If ever there was a simple, uncomplicated case, it's this one.
If ever there was a place to stash away a limping car with a hot license number.

定義：Oxford Advanced Learner's Dictionary 第 9 版