Complex sentence: They decide to go back to Time Safari (They are by a swarm of bat-like creatures on the way, and Lucas is killed), only to find that it is flooded, making the machine inoperable, and that Hatton has died.
Split into simpler sentences: They decide to go back to Time Safari, though are attacked by a swarm of bat-like creatures on the way, resulting in Lucas being killed. They arrive, to find that it is flooded, making the machine inoperable, and that Hatton has died.