Complex sentence: Jack finds a boobie trapped labyrinth, in the centre of which there is a diamond which could send him back to his own time, but a mysterious stranger who has also entered the maze could put Jacks plans in jeopardy.
Split into simpler sentences: Jack finds a boobie trapped labyrinth in the centre of which there is a diamond which could send him back to his own time. However, a mysterious stranger who has also entered the maze could put Jacks plans in jeopardy.