苏珊（梅丽莎·麦卡西MelissaMcCarthy饰）是中情局专门协助处理危险任务却不为人知的后勤人员，她的搭档布莱德利（裘德·洛JudeLaw饰）在一次行动中突然失踪，也波及另一位顶尖中情局特工瑞克（杰森·斯坦森JasonStatham饰）的安危。为了找出搭档的下落，拯救这个岌岌可危的世界，苏珊自愿充当卧底，混进史上最危险的军火商集团，试图查出事情的真相，并与蛇蝎美女头目（萝丝·拜恩RoseByrne饰）斗智斗勇。然而在英勇救难的惊险过程中，苏珊发现事情远没有她想象的那么简单……

本片模仿美国西部片，任用当时法国影坛两大性感女星芭铎和莫罗。她们扮演两个江湖女侠，取代美国西部片的牛仔角色，专门在拉丁美洲行侠仗义，打抱不平。其中玛丽娅是在拉美进行无政府主义革命运动的爱尔兰政客的女儿，她在父亲被杀后，在马戏团偶遇另一个也叫玛丽娅的女郎。她们结下深厚友谊并目睹拉美人民的贫困和肆虐的暴力，决定利用自己的聪明天赋来协助革命运动。

表面上，雪莉（珍妮弗·加纳JenniferGarner饰）是一名普通的大学研究生，实际上，她已为名为SD6的秘密情报组织工作多年。在同男友结婚之际，雪莉决定向其公开自己的真实身份，没想到男友却因此被组织的安全人员暗杀。愤怒中，雪莉选择了“罢工”，之后亦遭到了抹杀。　　危机之中，雪莉知道了自己的父亲杰克（维克托·加柏VictorGarber饰）也是和自己一样的秘密特工，并且，在背后扶持SD6的并非国家组织，而是拥有强大武力的反动分子。于私于公，雪莉和SD6都有着不共戴天之仇，她回到了SD6，但此时，雪莉的身份已升级成了为CIA工作的双重间谍，在危险和考验之中，雪莉的任务只有一个，那就是彻底铲除SD6。

Sydneyfindsherselfface-to-facewithherlong-lostmother,IrinaDerevko,whoseintentionsforherdaughteraremadechillinglyclear.However,SydneymanagestoescapeandrejoinJackandWillintheirescapefromTaiwan.AfterarrivingbackinLosAngeles,SydneycontinueshersearchforVaughn,notknowingifheisdeadoraliveafterbeingsweptawaybyawallofwaterinTaipei.Will'slifeisforeverchangedwhenhelearnsthetruthaboutSD-6andSydney'slifeasadoubleagent.Also,DixonmustdecidewhetherornottoinformSloaneofSydney'ssuspiciousactivities.ButJackintervenesandcoversforSydneywholaterfindsVaughnwhohelpshertrytotrackdownhermotherIrinawho'ssearingforaRimbaldiartifactcalled'theBible.'

HavingwokenupinHongKong,withnomemoryforthelasttwoyears(!),SydneyreturnstoLosAngelestotrytopiecetogetherthelasttwoyearsofherlifeanddiscoversthefatesofherfriendsandfamily:VaughnhasmarriedthinkingthatSydneywaslongdead;MarshallishavingababywithCIAtechexpertCarrieBowman;andDixonisnowthenewdivisionheadoftheL.A.officebranchoftheCIA.SydneyalsolearnstheshockingfatesofJackandSloane;theformerisinCIAcustodyforcommunicatingwithIrinawhomstillisinhiding,whilethelatterislivinginSwitzerlandunderhousearrestinexchangeforco-operationwiththeCIA.SydneyisgrantedtemporaryCIAclearanceonacasethatmayhelpherregainhermemoryandshemeetsanewenemygroupcalledTheCovenant.

SidneyBristowisacollegestudentwhohasanunusualjob–sheisaspyworkingfortheCIAundersecretconditionswherenotevenherfriendsknowswhatshedoes.WhenherboyfriendproposesSydneytellshimwhatshedoesforalivingandheremployerskillhiminlinewithprocedures.DecidingtoleavetheagencybeforetheykillhertooSydneydiscoversthatshehasactuallybeenworkingforSD6,anagencythatisactuallyashadowycriminalorganisationworld-wide.SydneyjoinstheCIAandworksasadoubleagenttohelpCIAAgentVaughntobringdownSD6.ShefindsthatherfatheristheotherdoubleagentwithinSD6andthepairworktogether.WhilefollowinghermissionstouncovertheworkofthepropheticRambaldishemustfeedinformationbacktotheCIAwithoutblowinghercover.

Fivemonthslater.SydneyquitstheCIAandjoinsaBlackOpsunitcalled"AuthorizedPersonnelOnly"alongsideDixon,Jack,Vaughnand...Sloanewhomforlimitedimmunityisco-operatingwiththeAPO.Meanwhile,thetruthSydneyfoundoutinWittenbergendangersherrelationshipwithJack,andeventuallysherevealstheawfultruthtoVaughn:aboutherfatherhavingIrinamurderedoverayearearlier.