While looking for a cue for Alzheimer's Disease, Will Rodman (James Franco) tests his drug on apes in preparation for human trials. After finding his drug enhances the apes' intelligence he prepares to present his finding to secure the funding for human trials - until the intelligent ape escapes, causing havoc.
Any further experiments are off the cards and all of the apes are put down. It is later discovered that the intelligent ape was merely protecting a secret baby which Will decides to adopt.
The young ape, later named Caesar (Andy Serkis), grows up in the care of Will who finds that it displays an abnormally high intelligence rate, but things start to become complicated when Caesar's over-protective nature tears him apart from Will when he is impounded.