president trump it s believed in talking with the russians in oval office, was talking about an isis plot, what could be the biggest plot to take down a plane since 9/11. tonight, by sharing that information, are the lives of sources at greater risk, and what about our relationship with the ally who gave the white house that information in the first place. here s brian ross tonight. reporter: what s at risk tonight, according to current and former u.s. officials, is the life of a spy inside isis, placed there by israel, providing sensitive information about terror plots against america on the condition the u.s. keep the source secret. the real risk is not just this source, but future sources of information about plots against us. reporter: the current intelligence from inside isis involves an active plot to bring down a passenger jet en route to the u.s., with a bomb hidden in a laptop that the u.s. believes can get through airport screening machines undetected. the information i