Behan's absurdist tragi-comedy, The Hostage, was originally written in Irish Gaelic and performed in that language as An Giall at the Damer Hall, St. Stephen's Green in Dublin, Ireland, in 1957. Following the success of that production, Behan translated the play into English and Joan Littlewood, the innovative director of the Theater Workshop in London agreed to direct it. The premiere of The Hostage opened on the 14th of October, 1958, at Littlewood's Theater Royal in Stratford, London.

The Hostage received mixed reviews upon its debut, but as Littlewood's Theater Workshop became increasingly well-known and respected, interest in the original production increased. The work has subsequently become one of the pillars upon which Behan's reputation rests, and the original Littlewood production has since become recognized as evidence of the Theater Workshop's important role in Postwar British theater.

The play's structure is loose and some of the dialogue comes straight out of on-the-spot improvisations, but the basic plot revolves around the IRA's kidnaping of a British soldier. The IRA plans to use the hostage as a bargaining chip for the release of an IRA prisoner who is due to be executed in Belfast the following morning. The British soldier is held prisoner in a rough-and-ready Dublin lodging house that also functions as a brothel, and while he is held there, the prisoner's presence causes much discussion about past and present Irish nationalism and Britain's involvement in colonial affairs in general.

The play is written in a non-realist style; characters frequently burst into song and sometimes into song-and-dance routines, and Behan consistently tries to undercut seriousness with humor. Littlewood tried to act and direct her plays in a way that would break down the "fourth wall" between actors and audience. It is a key text of the Absurdist theater movement, a movement that influenced later generations of playwrights such as Tom Stoppard and Harold Pinter. The play is especially important because it represents the intersection of British and Irish theater that occurred prior to the escalation of hostilities in Northern Ireland.