British soldier [Jody](forest-whitaker) finds himself ensnared by the IRA while off duty in Ireland, when he's captured by [Fergus](stephen-rea), Jude (Miranda Richardson), Maguire (Adrian Dunbar), and others. They intend to exchange him for a fellow IRA prisoner being held by the British government. During his three-day captivity, Jody and Fergus form an unexpected bond as they converse and share their lives, with Fergus showing a rare gentleness by removing the sack from Jody's head.
Jody opens up about his girlfriend, Dil, back in London, stating she fits his ideal image of a woman. As they discuss morality and choices, Jody shares a parable about a scorpion and a frog. >“I couldn't help it,” said the scorpion, “it's in my nature.” This story resonates deeply with Fergus and serves as an allegory for their diverging paths. Jody, understanding Fergus’s inner turmoil, entrusts him with his wallet, asking him to deliver a message to Dil, expressing that he was thinking of her at the end.
When the moment to execute Jody finally arrives, Fergus takes him into the woods, removes the hood, and finds himself unable to pull the trigger. In a desperate act, Jody frees himself and makes a run for it, only to be tragically struck by a British armored vehicle amid a chaotic raid on the hideout. While two IRA members are killed, Fergus, Jude, and Macguire manage to survive.
Determined for a fresh start, Fergus disappears and ventures to London in search of Dil. He finds work as a day laborer and locates her at a hairdressing salon. Under the new alias 'Jimmie', he engages in conversation with Dil, thanks to the bartender, Col (Jim Broadbent), playing the role of matchmaker. However, as they grow closer, Dil’s volatile relationship with another man complicates matters, leading to Fergus intervening when an altercation arises.
Their connection deepens, leading to a shared intimacy, but the relationship takes a serious turn when Fergus discovers that Dil is a transgender woman. Initially repulsed, he grapples with his feelings as he processes this revelation. After a night of contemplation, Fergus reaches out to Dil once more, apologizing for his reaction, and they begin to rebuild their relationship amidst hidden dangers.
However, Fergus soon learns that the IRA is still monitoring him, and he faces the grim reality of being pulled back into their operations. Jude informs him of a forthcoming assassination assignment in London, using Dil as leverage to compel Fergus’s cooperation. As tensions rise, Fergus tries to protect Dil by advising her to disguise herself as a male.
Despite his intentions, Dil ultimately leaves the hotel where she was supposed to hide, leading to a precarious situation that ends with a confrontation involving Jude. When the dust settles, Fergus finds himself in an impossible position, and after a violent encounter where Dil manages to defend herself, he is left to face the consequences alone.
As the story culminates, Fergus takes the fall for the murder, resulting in his imprisonment. In a poignant final scene, Dil visits him, hair regrown and hope in her heart, as they discuss what awaits them on the other side of his sentence. Fergus explains why he chose to take the rap for her by echoing Jody’s parable of the scorpion and the frog, concluding with the powerful statement, “it’s in my nature (to do the right thing).”
