to be a bomb which attaches itself to the murderer of the bomb's owner, which is John, and begins a ten-minute countdown. Unwilling to die, John handcuffs himself to Gwen and swallows the key in order to force Torchwood to remove the bomb. Gwen formulates a plan to use the Rift at the car park to contain the explosion, but at the penalty of her own life. Jack and Owen catch John and the rest of the team at the car park where John arrived and inject him with the team's DNA, thus confusing the device into detaching from John. Jack throws the bomb into the Rift where it detonates. John then regurgitates his key to free Gwen and agrees to leave. Before leaving, John tells Jack that he found Gray. Production Writing and filming The development of the episode commenced when executive producer Russell T Davies received an email from his agent, telling him James Marsters was interested in appearing on the series. Chris Chibnall wrote the episode "absolutely" for Marsters, and wanted Hart to become a conflict for Jack Harkness. Marsters believed that Hart was somewhat of a doppelganger to Harkness. After scripting was complete, Marsters did not need to discuss with the directors because he felt the script was self-explanatory. Originally, Captain John was going to come through the Rift on a "pandimensional surfboard" similar to the one found in the Doctor Who episode "Boom Town", Chibnall changed it because the production team decided that "it would look cooler if John just calmly walked out of the Rift, as if it was the sort of thing he might do every day". The episode was filmed in Cardiff in July 2007. The first meeting between Jack and John at the nightclub was written to be akin to a Spaghetti Western. Instead of fighting, it was decided that they would kiss first, so that the audience "don't see it coming". The following fight scene was intended to be "sexy, rather than brutal", similar to the naked wrestling scene in the film Women in Love. While the scene only lasted one minute on screen, much more was filmed, so much that it took a whole day to shoot. 80% of the acting in the scene was done by Marsters and Barrowman themselves, instead of stuntmen. The style of fighting was similar to what Marsters was used to, and was, according