S4·E17 The Falcon Manifesto

Matt has a shot at cheaply buying a small yacht and insists Summer should chip and move in. Mitch falls instantly in love with strangely aloof and secretive Kate McCoy. Only after her sudden death is diagnosed poisoning he learns from his cop mate Garner that Kate was an undercover alias of D.C. investigative reporter Catherine Larsen, who found out about secret arms deals.