catch sb in the act

catch sb in the act AND catch sb red-handed — поймать с поличным, поймать на месте преступления, схватить за руку

Example 1: He takes too many risks. One day they'll catch him in the act. — Он слишком рискует. Настанет день — и его поймают с поличным (схватят за руку).

Example 2: There's no point trying to deny it. You were caught red-handed trying to break into the shop!

See also
[с поличным ]
[catch sb off guard]
[take sb aback]
[catch sb with one's pants down]