FBI agent Neville Flynn boards a flight from Honolulu, Hawaii to Los Angeles, escorting a key witness to testify against a mob boss at an upcoming trial. An on-board assassin releases a crate full of hundreds of deadly venomous snakes in an attempt to eliminate the witness. Flynn and a host of frightened passengers and crew must band together to survive the slithery threat.

The teenager Madison McBride is traumatized by the loss of her deranged father when she was nine years old and the suicide of her beloved brother Brandon one year ago. She decides to join the Richard Miller University, where Brandon committed suicide, to overcome her demons. While walking to her dorm, she meets the weird janitor Wilbur Mackey that tells her that the place is haunted.

When the pets accidentally get separated from their vacationing owners, Chance, Shadow, and Sassy navigate the mean streets of San Francisco, trying to find their home across the Golden Gate Bridge. But the road is blocked by a series of hazards, both man and beast.

A weekend at a lake house in the Louisiana Gulf turns into a nightmare for seven vacationers as they are subjected to fresh-water shark attacks.