瓮中捉鳖

wèng zhōng zhuō biē

lit. to catch a turtle in a jar (idiom)

fig. to go after easy prey

wèng

variant of 甕|瓮[weng4]

zhōng

(bound form) China; Chinese

zhuō

to clutch

biē

variant of 鱉|鳖[bie1]