What if your husband - the man you love and share a home and bed with, turns out to be a terrorist?

Kurbaan, produced by Karan Johar and directed by Rensil D’Silva, constructs this unimaginably tortured situation and then squanders it. The film has ambition but it is too flawed and simplistic to explore issues like religion, violence and the politics of terrorism with any conviction or gravitas.

Rensil, who wrote the screenplay from a story by Karan Johar, is impatient to get to the central conflict. So, the romance between Avantika, played by Kareena Kapoor and Ehsaan Khan, played by Saif Ali Khan, is brisk.

Both are professors at a university in Delhi but we see her teach exactly once. They spend more time drinking coffee, romancing and believe it or not, kissing in the staff room. I had no idea college professors had this much fun.

When Avantika gets a call asking her to return to New York University, the two rush into marriage and fly to America. It all seems perfectly sunny until a neighbour reveals to Avantika that things aren’t quite what they seem.

In a quietly frightening, nicely done scene, Avantika discovers that Ehsaan is a terrorist. In fact, his name isn’t Ehsaan at all – at various moments in the film, he’s called Altaf, Tabrez and eventually Khalid.

Ehsaan won’t allow his fellow terrorists to kill his wife because she is pregnant but also because somewhere in the course of scheming, he’s fallen in love with her.

He threatens to have her father killed and keeps her quiet and well-fed, a prisoner in her own home.

Their tense, volatile relationship is gripping and the performances are heart-felt. Saif’s understated menace is the perfect foil for Kareena’s aching vulnerability. Even Vivek Oberoi, playing Riyaaz, an investigative journalist who infiltrates the sleeper cell, forgets his Mission Istanbul-style posturing and acts.

But the performances, melodious music and snazzy camerawork cannot camouflage Kurbaan’s specious logic and faulty writing.

The most critical plot points in the film make little sense—the FBI have Ehsaan’s photograph and history on their records. An FBI agent barks—"I want this man found and found fast"—and yet, Ehsaan roams around freely.

He has a driver’s license and a job teaching a course on, get this, the Muslim identity in the Modern World.

When Avantika realises that her neighbours are dubious, she doesn’t call the cops like any normal person would. Instead, she goes alone, at night, into their basement and stumbles on a dead body.

Riyaaz goes one step further. When he figures out that there is a sleeper cell, he doesn’t call the FBI. Instead he declares: "I’m going to deal with it myself" and joins the gang.

The terrorists aren’t very bright either. After one dinner, they enlist Riyaaz into the group. People dating each other probably spend more time looking up for partners on Google than these guys do before bringing in Riyaaz on a plan to blow up subway stations.

And then, there’s the Kareena-Saif lovemaking scene that has generated reams of newsprint. Yes, it is bold by Bollywood standards. You see her bare back. It’s aesthetically done but again, the logic for it is laughably silly – she has to get the names of the stations that will be blown up. So she seduces him and then digs into his desk to get the map with the stations marked out. She says, "Kya hum ek raat ke liye sab kuch bhool kar phele jaise nahin ho sakte", but he doesn’t wonder why she’s being so friendly all of a sudden.

In a regular Hindi film, viewers are happy to suspend disbelief. But a film that deals with such serious, intricate issues cannot demand that comfort.

Even the little bloopers here jump off the screen: Avantika, is under house arrest but she still has talon-like manicured nails and this was my favorite moment, Riyaaz, who has just returned from reporting in Iraq, gets off a plane and solemnly declares: "Iraq is a mess".

Clearly Rensil is a talent to watch. He isn’t afraid to take risks but his ambition and good intentions aren’t matched by the sophistication that this project required.

Kurbaan is a disappointment.