Growing Home

At Number 3 Ramshorn Drive, a modest house cluttered with antiques, a goldfish named Toasty lives in an ornate octagonal fish tank that has been in the Tupper family for generations. The Tuppers, Mr. and Mrs. Tupper and their daughter Jillian, are antiquarians who buy and sell old objects at their store, Re-STORE-ation. Toasty is their only pet, named because Mr. Tupper believes a fish tank without a fish is like a toaster without toast.

From his tank in the round foyer, Toasty can see the entire first floor. He resents that Jillian's affections belong to Ivy, a small houseplant she chose at the grocery store. Ivy and Toasty bicker constantly. Each morning, Toasty splashes water at Ivy, and the water travels an impossibly far distance to land neatly in her planter. Neither notices this oddity, nor does Ivy question her ability to stretch her leaves across the first floor, a power she gained after that first splash.

One day, Ivy discovers Arthur, a spider trapped under a typewriter key. Arthur had been living in a bookstore and was accidentally relocated when the Tuppers brought home an antique desk. Ivy frees him and splints his injured leg with a toothpick. When Arthur says he must return to the bookstore, Ivy begs him to stay, desperate for a friend. Arthur agrees to remain while he heals, drawn by the idea of friendship, something he has only read about in books. He settles on top of the bookcase, using a large book called The Birds of America as his bed, which Ivy retrieves from a secret compartment in the desk.

Jillian soon brings home a new plant named Ollie as a companion for Ivy. Toasty tells Ivy that a "duo" means they must fight, and Ollie faints in terror. Arthur corrects Toasty, explaining that a duo simply means a pair. Ollie shares that he came from a school nurse named Mrs. Cannella and secretly loves singing but is too shy to reveal it. Ivy, Arthur, and Ollie form a trio, while Toasty refuses to join.

The Tuppers bring home an antique birdcage painted an ugly green. When Mrs. Tupper sets it on the kitchen table, it nearly crushes Arthur. Ollie instinctively touches Arthur, and Arthur vanishes. Simultaneously, Ivy lifts the birdcage's edge with one leaf so Arthur can escape. Neither plant understands these new abilities. After the Tuppers leave, the trio declares the abilities to be magic, while Toasty feels excluded and jealous.

The next morning, the powers have vanished. A bumblebee named Louise flies into the house while fleeing a canary she calls "the Scary Canary" and falls into Toasty's tank. Ivy rescues her. The canary, Sunny, follows through the front door and flies straight into the birdcage, revealing herself to be a frightened pet rather than a predator. Arthur types a flyer announcing Sunny has been found, and Louise carries it outside. The flyer reaches Sunny's owner, Mrs. Bonnetby, who had already called the police to report Sunny missing. Mrs. Bonnetby arrives with officers in tow. During the commotion, Mr. Tupper's hash browns catch fire, and Toasty frantically splashes water trying to help. Ivy observes Toasty's selfless effort and begins to see past his grumpy exterior. After Sunny is reunited with Mrs. Bonnetby, Ivy realizes that friendship is more valuable than being the favorite or having superpowers.

That evening, the trio tries again to activate their powers but fails. When Toasty splashes them in annoyance, both plants' abilities suddenly return. Arthur deduces the connection: The water from Toasty's tank is the catalyst. Ivy gains super-strength and Ollie gains the power of invisibility each time they absorb splashed water through their roots. Arthur, who cannot absorb water, receives no powers but identifies his own superpower as reading. Toasty is thrilled and fantasizes about leveraging his importance for endless cheese puffs. Arthur also shares that goldfish originated as silver carp in ancient China and tells Toasty that soccer originated there too, a connection that delights the group.

The Tuppers take the birdcage to their store. Arthur, hiding inside it, is carried along. At the store, he realizes his former bookstore is right next door and faces a choice: return to his solitary life or stay with his friends. He chooses to stay, recognizing that books can fill much of his heart but not all of it.

A buyer named Mr. Brookstone, a squat man in a monocle and purple shoes, arrives at the store and examines the birdcage. He asks about an octagonal fish tank, unsettling the Tuppers. Mr. Tupper connects a small infinity-sign mark on the birdcage to an identical symbol on Toasty's tank. Both bear the mark of Augustus Octothorpe, an alchemist who lived over 150 years ago. Octothorpe traveled to Brazil seeking neodymium, a rare earth element he hoped would turn metals into gold. He failed but discovered neodymium could give objects extraordinary properties. He completed only two of four planned creations: the birdcage, which granted flight, and the fish tank, which failed at its original purpose but gave abilities to whatever absorbed its splashed water. Octothorpe fled from pursuers drawn by his secretive work, and the objects eventually scattered until both ended up with the Tuppers.

Sensing something wrong about Brookstone, Mr. Tupper refuses to sell him the birdcage. Mrs. Bonnetby buys it for Sunny instead. Afterward, the Tuppers discuss selling Toasty's tank to address their debts. Arthur, hidden in Mr. Tupper's hat, overhears and races home to warn the group.

The trio resolves to save Toasty. That night, they ask Toasty to splash them, and Arthur begins typing a note to Jillian reading "SAVE TOASTY." He completes only "SAVE TOAST" before someone tries the front door. Arthur recognizes Brookstone, who has come to steal the fish tank. Ivy fills the kitchen sink, and Toasty, trusting his friends despite his fear, leaps from his tank into the distant sink. Brookstone picks the lock, enters with a pump and hose, and begins draining the tank. Arthur launches himself at Brookstone's face to stop him, but Brookstone flicks Arthur off violently, sending him crashing into the wall with four newly broken legs.

Ollie then sings a deep, eerie solo in a powerful baritone, a talent he has kept hidden. The mournful sound unnerves Brookstone, who backs against the bookcase. Ivy, made invisible by Ollie's touch, climbs to the top and finds Arthur badly injured. Arthur urges her to push The Birds of America off the edge. The enormous book strikes Brookstone and knocks him unconscious. The thump wakes the Tuppers, who call 911. Jillian discovers the nearly empty tank and sobs, believing Toasty is gone. Hearing Jillian cry his name, Toasty realizes she truly loves him. Mrs. Tupper finds him safely in the kitchen sink.

Mr. Tupper discovers that The Birds of America is a valuable first edition. Its sale pays off all the family's loans and funds a college savings account and a small greenhouse for Jillian, who keeps a section for dandelions, honoring the wish she once made on a dandelion puff. When Mrs. Tupper spots Arthur nestled among Ollie's leaves with toothpick splints on his legs, she reaches for the Spider Smasher, but Jillian insists they must help others, even spiders. Arthur is allowed to stay.

In the following weeks, Ollie tells his friends about feeling invisible at a florist shop and lonely in the school nurse's office. Shortly afterward, he blooms for the first time, producing three lavender-blue flowers. Louise returns with a note from Sunny announcing a visit. Ivy reflects that the old Ivy could not have celebrated another plant's blooms, but this Ivy can. Toasty, still grumpy on the surface, finally feels warmth he recognizes as love. He swims four figure eights, splashes his friends, and demands cheese puffs and soccer. The four of them accept that they are not just friends but family.