I'd read there were something like a million viewers, had a growing fan base so I can't understand why the aren't continuing it. Really disappointing! 
EPISODE 6 SPOILERS BELOW!:
Tyrian, episode 6 really showed Nathan's decent into madness, searching for his son. We then find out Gabriel has been haunting a woman named Lara who has checked herself into hospital with her baby, and been diagnosed with postpartum psychosis due to seeing Gabriel since she gave birth. She meets with her grandmother who tells her she really is seeing a ghost and the ghost is actually her great great uncle Gabriel. She gives her the Appleby's information, photos, where they lived etc. Lara then takes her little baby and leaves the home after stealing her partner's car keys. She drives to the Appleby's estate and begins investigating. While this is happening in the future, back in the past Nathan is continuing to further lose his mind and is becoming unloving and aggressive towards Charlotte. He drives her away, and she ends up being admired by another man. Nathan ends up seeing Gabriel, who tells him to join him on the other side to take care of him. What follows is Nathan preparing to kill himself to be with his son. Charlotte gets word of his intentions and races back just in time. She holds Nathan while he cries and unknowing to Charlotte, Gabriel is stood in the room the whole time. Nathan accepts his son is gone and that he has to forgive himself. He tells him he's sorry and he loves him for the last time. What then happens is the farm workers pull a car out of the ground, and Lara is there watching it happen. It's her car, she had an accident and was killed but her baby survived. Gabriel tells her she is his new mummy and she can look after him now. She takes his hand and they walk away together. Some time later, Nathan is woken from his sleep by noise downstairs. He begins to walk down the stairs and stops when he sees a group of young men and women in 20s style dress. By the looks of it they were doing a seance. When they see Nathan, the refer to him as "the infamous Nathan Appleby" and ask him, "tell us how your killed your wife" cue a horrified and confused expression from Nathan, and it ended there.
Oh boy that was long but I wanted to be thorough!! 
Colin Morgan was fantastic in episode 6, so gutted it won't continue!