The circus is in town, but their resident gorilla, Congo, is ailing and not able to perform. When his trainer tries to give him a shot of penicillin, the ape escapes and runs into town, causing terror among the residents. Chuck and P.T. take to the skies to track the sick animal.
| Name | Type | Role | |
|---|---|---|---|
| Terry Burnham | Guest Star | Josie Fisher | |
| Frank Gerstle | Guest Star | Capt. Brown | |
| John Harmon | Guest Star | Mr. Thatcher | |
| Peter Adams | Guest Star | Father | |
| Marie Blake | Guest Star | Mrs. Thatcher | |
| Tom Voigt | Guest Star | Son | |
| George Barrows | Guest Star | State Tropper | |
| Gene Reynolds | Guest Star | Hal Neilson | |
| Ann Morrison | Guest Star | Eva Fisher | |
| Nestor Paiva | Guest Star | Ed Fenton | |
| Allen H. Miner | Director | ||
| Kenneth Tobey | Actor | Chuck Martin | |
| Craig Hill | Actor | P.T. Moore |