空姐凯西在执飞国际航班时结识乘客艾力克斯，两人在曼谷的一间酒店发生一夜情。第二天早上，她从宿醉中醒来，发现艾力克斯浑身是血躺在床上，已经气绝身亡。酗酒成瘾的她完全记不起昨晚发生的事情。

凯西为了找到在曼谷当晚一起就餐的名叫米兰达的女性，她假装是投资人进入大地球仪资产公司。看到公司派遣专业经理人前来商谈业务，凯西落荒而逃，途中打破了公司的兔子装饰品。随后她接到联邦调查局探员怀特的电话，邀她再次前往局里问话。

凯西从罗马回家发现家中此前有人破门而入，她找到安妮求助。安妮联系联邦调查局探员怀特，希望他们对萨布丽娜展开质询，调查有关米兰达的线索。怀特称没有从萨布丽娜口中得知有用信息。

凯西来到安妮家中，与麦克斯一起拼接带回的碎纸条。她从中发现一条可疑航线，飞机每日从新泽西州的泰特波罗机场飞往缅因州的波特兰，在波特兰短暂停留后即刻返航。凯西认为可能与米兰达有关，她打听到同事内特在该航空兼职，借此登上这班飞机。

为了还客户人情，安妮带着一小封药物进监狱，会见律所代理的另一位客户。这名客户听到安妮传达的口信，得知亲人会被照顾，他果断吞下药片。凯西回忆起艾力克斯曾透露他在家办公，通过细节她推断出艾力克斯的公寓地点。

麦克斯严重受伤，被送进手术室。凯西声称匆忙之中丢失了存有证据的闪存盘。安妮认为她因酗酒产生妄想，并因此与凯西绝交，将她赶出家门。安妮同时向律师递交了辞职信。哈蒙德和怀特来到凯西到过的仓库，发现里面已经被彻底清空。

米兰达听到凯西的解释，相信她只是一名空乘。两人交换信息，艾力克斯可能因为偷藏起客户的资金而被杀害。米兰达决定听从凯西的意见，请安妮与联邦调查局沟通，保障两人的安全。安妮对此完全没有把握，米兰达建议凯西与自己一起离开美国，躲避维克多的追杀。

米兰达从塞西莉亚口中得知维克多的行踪，维克多告诉米兰达派遣菲利克斯前去曼谷谋杀艾力克斯的经过。米兰达击杀维克多，拿到艾力克斯用于记载藏钱线索的小说，前往罗马解救凯西。

Now almost a year sober, Cassie has started fresh in LA with her supportive new boyfriend, Marco. But her side gig moonlighting as a CIA asset soon finds Cassie entangled in an international murder mystery… again.

After revealing her secret side gig to Annie and Max, Cassie sets out to find the woman who's been impersonating her – and zeros in on enigmatic new flight attendant Grace.

A cryptic text leads Cassie to search for Megan in Reykjavík, where Shane grows increasingly suspicious of his friend’s erratic travels. Back in LA, Annie and Max face unexpected turbulence.

After attempting to get Megan safely out of Reykjavík, Cassie fears she’s being framed for murder when two bodies are found in Echo Park.

After finding potentially incriminating photos in Benjamin’s office, Cassie seeks assurances from Shane – and continues to avoid Marco – while Megan searches for an all-important lockbox.

Cassie faces hard truths about her path to sobriety while visiting her mom as Megan attempts to reconnect with her family, who are reluctant to welcome her back.

Cassie, Shane, Annie, and Max attempt to run down clues in the string of murders – which continue to point to Cassie as the main suspect.

Cassie manages to connect the dots in a far-reaching conspiracy, while Megan tries to make amends with Shane.