Trama

A family moves into a new home, unaware that a dark secret from the house's past will unleash a malevolent force in the backyard pool.

Forced into early retirement by a degenerative illness, former major league baseball player Ray Waller moves into a new home with his wife and their two children. The new home comes complete with a backyard swimming pool, but a deep secret surfaces and unleashes a malevolent force that will drag the family into the inescapable depths of terror.—Universal Pictures

Hopeful of a fresh start, former big-league third baseman Ray Waller, his wife, and two kids move into a beautiful house with a spacious swimming pool in the backyard. And right from the start, the new home seems too good to be true. After all, Ray's doctor has recommended water therapy. But the more Ray's health improves, the more the rest of the family experiences strange, hair-raising occurrences. Some places come with secrets that defy logic. What evil lurks beneath the pool's sinister waters?—Nick Riganas

The former baseball player Ray Waller, his wife Eve, and their children Izzy and Elliot are looking for a house to settle down. Ray has a degenerative disease and was forced to retire as a player. When they see a beautiful house with a backyard swimming pool that they can afford and close to the school where Eve will work and Izzy and Elliot will study, they immediately buy it. The doctor says that the swimming pool will help Ray to have a better condition. Soon they learn that the swimming pool is connected to a water spring. But Elliot first and Izzy later sees a weird creature in the bottom and believes the swimming pool is haunted. The Wallers decide to give a party in the swimming pool to their neighbors in the community and weird things happen. Further, Eve learns that a girl, Rebecca, disappeared into the swimming pool fifteen years ago. She decides to investigate and learns the secret of the swimming pool.—Claudio Carvalho, Rio de Janeiro, Brazil

From Wikipedia:

In 1992, a young girl, Rebecca Summers, goes out to her family pool one night to retrieve a toy boat belonging to her terminally ill brother, Tommy. While she tries to get the boat, something in the pool pulls her underwater. This is a dumb premise that leads to a bloodless series of embarrassingly bad non-events.

In the present day, the Waller family-Ray, Eve, and children Izzy and Elliot-are seeking a new, permanent residence after Ray has been forced to retire from his baseball career due to illness. They decide to purchase a house with a swimming pool in the backyard, especially after hearing that the pool would be good for Ray's condition. Ray scratches his hand while working to clear out the pool in the back yard. When the pool maintenance come to inspect it, they reveal that the pool is essentially self-sustaining, taking its water from an underground spring in the area.

As he spends more time in the pool as part of his therapy, Ray's illness seems to go into remission. However, Eve becomes concerned at the changes she sees in her husband. Izzy and Elliot each get attacked by something in the pool, and the family cat goes missing. During a pool party, their realtor, Kay, tells Eve about the previous owners' daughter Rebecca Summers drowning in the pool shortly before Ray seemingly forces a child underwater and almost drowns himself, although this is attributed to a side-effect of his illness.

Tracking down the Summers family after learning that there is a long history of disappearances in the house, Eve meets with Lucy, Rebecca's mother. Lucy explains that the water that now sustains the pool was once part of a healing spring, but in order to use the water someone else must be sacrificed to it; Lucy was compelled to sacrifice Rebecca to the pool's entity to heal Tommy's illness. Eve is horrified to realize that Ray is now being healed by the pool but it will take one of the children as a sacrifice.

Eve returns to the house to find that Ray is being directly controlled by the entity, which traps Elliot in the pool and attempts to kill Izzy. Eve tries to save her son while Izzy confronts the entity possessing her father, eventually assaulting him with a baseball bat. Eve manages to retrieve an unconscious Elliot, and is guided to the surface of the pool by Rebecca's spirit. Once back in the yard, Izzy's assault and Elliot's condition help Ray regain control of himself. To stop the entity attacking his children, Ray sacrifices himself to it.

Deciding to remain in the house so that no one else falls victim to the entity, Eve, Izzy and Elliot make arrangements for the pool to be filled in to stop such a thing happening again.