 In " Fragments " , Captain John returned in holographic form , stating that he is going to destroy Jack 's life , revealing a holographic image of his lost brother Gray . Continuing in " Exit Wounds " , Captain John is revealed to have rescued Jack 's brother Gray from a group of sadistic captors , only to learn too late that Gray had been driven insane through being tortured over the years . Molecularly bonding a bomb to John 's wrist to force him to obey his orders , Gray had John set off multiple bombs throughout Cardiff before taking Jack back in time to 27AD , where Jack is buried alive at the site that would become Cardiff in the future . However , John betrays Gray by leaving a tracking device on Jack in the shape of a ring , thus allowing Jack to be recovered by the Torchwood Institute and frozen in the morgue , escaping at the right moment to stop his brother . Having frozen Gray in cryopreservation , unwilling to witness any more death that day , Jack offers to help pinpoint another Rift event to allow John to leave , but John instead states his desire to travel Earth , commenting that he 'd like to learn what Jack finds so fascinating about the planet . 
