YOU SAID:

somewhere along the line he lost the plot

INTO JAPANESE

途中で彼は筋道を失った

BACK INTO ENGLISH

He lost his train of thought along the way.

INTO JAPANESE

彼は途中で考えがまとまらなくなった。

BACK INTO ENGLISH

He lost his train of thought mid-way.

INTO JAPANESE

彼は途中で考えがまとまらなくなった。

BACK INTO ENGLISH

He lost his train of thought mid-way.