S04E15: Mysterions
When Theodore discovers Alvin and Simon have a secret club, he promises not to tell anyone if they let him join.
Previous Episode 
Season 1
Talking Teddy
S1E1 / 03 Aug 2015
Principal Interest
S1E2 / 03 Aug 2015
A is for Alien
S1E3 / 04 Aug 2015
Jeanette Enchanted
S1E4 / 04 Aug 2015
Sister Act
S1E5 / 05 Aug 2015
Lil'T
S1E6 / 05 Aug 2015
What a Gem
S1E7 / 06 Aug 2015
Family Spirit
S1E8 / 06 Aug 2015
The App
S1E9 / 07 Aug 2015
Don Juan Theodoro
S1E10 / 07 Aug 2015
Albrittina
S1E11 / 10 Aug 2015
Simon for President
S1E12 / 10 Aug 2015
To Serve and Protect
S1E13 / 11 Aug 2015
Kickin It Old School
S1E14 / 11 Aug 2015
Clowning Around
S1E15 / 12 Aug 2015
Bully for You
S1E16 / 12 Aug 2015
My Sister The Weirdo
S1E17 / 13 Aug 2015
Turf War
S1E18 / 13 Aug 2015
Good Luck Mr. Whiskers
S1E19 / 14 Aug 2015
Who's Your Daddy
S1E20 / 14 Aug 2015
Mystic Mountain
S1E21 / 17 Aug 2015
Candy Confessions
S1E22 / 18 Aug 2015
Mojo Missing
S1E23 / 19 Aug 2015
Who's The Animal
S1E24 / 20 Aug 2015
Slippin’ Thru My Fingers
S1E25 / 21 Aug 2015
Driving Dave Crazy
S1E26 / 31 Aug 2015
Safety Third
S1E27 / 01 Sep 2015
Mister Manners
S1E28 / 02 Sep 2015
Tree House
S1E29 / 03 Sep 2015
Saving Simon
S1E30 / 04 Sep 2015
Back to School
S1E31 / 08 Sep 2015
Bromance
S1E32 / 09 Sep 2015
A Room of One's Own
S1E33 / 10 Sep 2015
Carts and Crafts
S1E34 / 11 Sep 2015
Going Green
S1E35 / 14 Sep 2015
Tattle Tail
S1E36 / 15 Sep 2015
Super Heroes
S1E37 / 16 Sep 2015
Shes Got Style
S1E38 / 17 Sep 2015
Kiss Conspiracy
S1E39 / 06 Nov 2015
House Guests
S1E40 / 09 Nov 2015
Theozilla
S1E41 / 10 Nov 2015
Doggone It
S1E42 / 12 Nov 2015
Mutiny
S1E43 / 13 Nov 2015
Reality or Not
S1E44 / 16 Nov 2015
Let Them Eat Crumbs
S1E45 / 17 Nov 2015
Ghost Rustlers
S1E46 / 18 Nov 2015
Alvin's Secret Powers
S1E47 / 19 Nov 2015
I Will Survive
S1E48 / 15 Feb 2016
Art for Art's Sake
S1E49 / 07 Mar 2016
Alvin's Got A Brand New Bag
S1E50 / 15 Feb 2016
Warbie
S1E51 / 20 Nov 2015
Mancave
S1E52 / 08 Mar 2016
Season 2
Dog Days
S2E1 / 09 Mar 2016
Dragon Dad
S2E2 / 10 Mar 2016
Members Only
S2E3 / 11 Mar 2016
The New Kid
S2E4 / 09 May 2016
Simon the Superb
S2E5 / 10 May 2016
The Sub
S2E6 / 11 May 2016
Lights Camera Uh Oh
S2E7 / 12 May 2016
Wax Dave
S2E8 / 13 May 2016
Brittany The Body Snatcher
S2E9 / 06 Jun 2016
Agent Smith
S2E10 / 07 Jun 2016
Baby Whisperer
S2E11 / 08 Jun 2016
Lets Make a Deal
S2E12 / 09 Jun 2016
Munk Man
S2E13 / 10 Jun 2016
Ride Along
S2E14 / 01 Aug 2016
Alvin's Wild Weekend
S2E15 / 02 Aug 2016
For Whom the Bell Tolls
S2E16 / 03 Aug 2016
iHear
S2E17 / 04 Aug 2016
Switch Witch
S2E18 / 08 Aug 2016
Double Trouble
S2E19 / 09 Aug 2016
Liar Liar
S2E20 / 10 Aug 2016
Suck Toad
S2E21 / 11 Aug 2016
Secret Admirer
S2E22 / 15 Aug 2016
Un-send!
S2E23 / 16 Aug 2016
The Orb
S2E24 / 17 Aug 2016
The Music Box
S2E25 / 18 Aug 2016
Special Delivery
S2E26 / 22 Aug 2016
Missing Miss Smith
S2E27 / 23 Aug 2016
Monster Madness
S2E28 / 24 Aug 2016
Super Girls
S2E29 / 25 Aug 2016
Held Back
S2E30 / 11 Oct 2016
Viral
S2E31 / 04 Mar 2017
Brothers of Dagarack
S2E32 / 04 Mar 2017
We're The Chipmunks
S2E33 / 14 Oct 2016
Save the Dance
S2E34 / 01 Nov 2016
Knights
S2E35 / 04 Nov 2016
Snake Charmer
S2E36 / 25 Feb 2017
It's My Party
S2E37 / 12 Oct 2016
Keeping Up with the Humphries
S2E38 / 13 Oct 2016
Overlooked
S2E39 / 11 Mar 2017
Wish Upon A Star
S2E40 / 11 Mar 2017
Jeanette's Secret Garden
S2E41 / 18 Mar 2017
Treasure Hunt
S2E42 / 18 Mar 2017
Summer Camp
S2E43 / 25 Mar 2017
Blabbermouth
S2E44 / 25 Feb 2017
He Said, She Said
S2E45 / 02 May 2017
Attack of the Zombies
S2E46 / 02 May 2017
The Temp
S2E47 / 02 Nov 2016
Parent Trap
S2E48 / 03 Nov 2016
Wacky Wednesday
S2E49 / 04 May 2017
The Chipmunk and the Catfish
S2E50 / 04 May 2017
Time Flies
S2E51 / 03 Jun 2017
Prank Calls
S2E52 / 03 Jun 2017
Season 3
The Karate Kidder
S3E1 / 10 Jun 2017
Playing Favorites
S3E2 / 10 Jun 2017
Back to Basics
S3E3 / 17 Jun 2017
Report Cards
S3E4 / 17 Jun 2017
The Cat Sitter
S3E5 / 24 Jun 2017
Addicted
S3E6 / 24 Jun 2017
Spoiler-Itis
S3E7 / 14 Aug 2017
Something Fishy
S3E8 / 15 Aug 2017
Baby Mama Drama
S3E9 / 16 Aug 2017
Ballet Boys
S3E10 / 17 Aug 2017
Oh Brother Where Art Thou
S3E11 / 30 Oct 2017
The Wall
S3E12 / 01 Nov 2017
The Gift
S3E13 / 02 Nov 2017
Theo Knows Best
S3E14 / 03 Nov 2017
Simsky
S3E15 / 17 Feb 2018
Lucky Day
S3E16 / 17 Feb 2018
Curiosity
S3E17 / 24 Feb 2018
House Pest
S3E18 / 24 Feb 2018
The Fugitives
S3E19 / 09 Mar 2018
Sherlock Chipmunk
S3E20 / 09 Mar 2018
Independence Day
S3E21 / 16 Mar 2018
Opposites Attract
S3E22 / 30 Mar 2018
Temporary Mom
S3E23 / 06 Apr 2018
Tee Fore Two
S3E24 / 13 Apr 2018
Dave Rebooted
S3E25 / 10 Feb 2019
Germs
S3E26 / 10 Feb 2019
Theo's Big Night Out
S3E27 / 17 Feb 2019
The Bodyguard
S3E28 / 17 Feb 2019
A Rose by Any Other Name
S3E29 / 23 Feb 2019
Queen Bee
S3E30 / 23 Feb 2019
Girls Night Out
S3E31 / 09 Mar 2019
Tables Turned
S3E32 / 09 Mar 2019
Switcheroo
S3E33 / 13 Apr 2019
The Paperboy
S3E34 / 13 Apr 2019
Pack Animal
S3E35 / 16 Mar 2019
The Haunted Getaway
S3E36 / 16 Mar 2019
Talking Teddy's Revenge
S3E37 / 02 Mar 2019
Snail-A-Palooza
S3E38 / 02 Mar 2019
School Alone
S3E39 / 30 Mar 2019
It Came from Outer Space
S3E40 / 30 Mar 2019
Pizza Dash
S3E41 / 06 Apr 2019
Glory Days
S3E42 / 06 Apr 2019
Across the Universe
S3E43 / 20 Apr 2019
Britt's Picks
S3E44 / 20 Apr 2019
The Devil Wears Rodentia
S3E45 / 10 Jun 2019
Career Day
S3E46 / 10 Jun 2019
Lost in Space...Camp
S3E47 / 11 Jun 2019
Super Hot Chocolate
S3E48 / 12 Jun 2019
The Great Chipmunk Detective
S3E49 / 13 Jun 2019
Guitar Hero
S3E50 / 17 Jun 2019
The C Team
S3E51 / 18 Jun 2019
Father Daughter Dance
S3E52 / 19 Jun 2019
Season 4
The Toy
S4E1 / 20 Jun 2019
Bloodline
S4E2 / 24 Aug 2019
Theodore's Calling
S4E3 / 27 Jul 2019
Clumsy Jeanette
S4E4 / 27 Jul 2019
Adventures in Babysitting
S4E5 / 10 Aug 2019
Alvin's Assistant
S4E6 / 10 Aug 2019
Big Bro Theodore
S4E7 / 02 Nov 2019
Granny Awards
S4E8 / 09 Nov 2019
Simon Says
S4E9 / 24 Aug 2019
Sing Like a Canary
S4E10 / 31 Aug 2019
Pirate's Life
S4E11 / 07 Sep 2019
World Record
S4E12 / 14 Sep 2019
Granny Awards
S4E13 / 16 Nov 2019
Sick Day
S4E14 / 23 Nov 2019
Mysterions
S4E15 / 17 Aug 2019
The Crow That Ate My Homework
S4E16 / 17 Aug 2019
Tour Bus
S4E17 / 21 Sep 2019
Game Show
S4E18 / 28 Sep 2019
Alvin Management
S4E19 / 05 Oct 2019
Time Capsule
S4E20 / 12 Oct 2019
Munk vs Machine
S4E21 / 19 Oct 2019
Shack Magic
S4E22 / 26 Oct 2019
The Exchange Student
S4E23 / 30 Nov 2019
Crystal Ball Birthday
S4E24 / 07 Dec 2019
Artsy Smartsy
S4E25 / 14 Dec 2019
The Crush
S4E26 / 21 Dec 2019
Best in Shoe
S4E27 / 28 Dec 2019
Royal Pain
S4E28 / 04 Jan 2020
Between a Rope and a Hard Place
S4E29 / 11 Jan 2020
World Day
S4E30 / 18 Jan 2020
Allergic Reaction
S4E31 / 25 Jan 2020
Lice-enced to Teach
S4E32 / 01 Feb 2020
Animal House Party
S4E33 / 08 Feb 2020
Dr. Zap vs Electroboy
S4E34 / 15 Feb 2020
Mega Bounce Battle
S4E35 / 22 Feb 2020
Gossip Guy
S4E36 / 29 Feb 2020
Chimpmania
S4E37 / 07 Mar 2020
Dad Jokes
S4E38 / 14 Mar 2020
The Chosen Chipmunk
S4E39 / 21 Mar 2020
Double Dangus
S4E40 / 28 Mar 2020
The Last Day of Summer
S4E41 / 04 Apr 2020
The Littlest Robot
S4E42 / 11 Apr 2020
You Troll
S4E43 / 30 May 2020
Life of the Party
S4E44 / 16 May 2020
Sick as a Chipmuck
S4E45 / 02 May 2020
Instant Gram
S4E46 / 23 May 2020
You Troll
S4E47 / 09 May 2020
Simon Saves the World
S4E48 / 25 Apr 2020Geizmo’s Day Out!
S4E49 / 13 Jun 2020
Unbored
S4E50 / 18 Apr 2020
A Very Merry Chipmunk
S4E51 / 06 Jun 2020
Season 5
Deserted
S5E1 / 29 Jun 2022
The Great Snack Off
S5E2 / 29 Jun 2022
Unboxing Day
S5E3 / 29 Jun 2022
Dave’s Pavilion
S5E4 / 30 Jun 2022
U-Fly
S5E5 / 30 Jun 2022
Yeti or Not
S5E6 / 30 Jun 2022
Taken
S5E7 / 06 Jul 2022
The Flying Beast
S5E8 / 07 Jul 2022
The Curse of Macbeth
S5E9 / 13 Jul 2022
Zeela the Great
S5E10 / 14 Jul 2022
Davey Boy
S5E11 / 21 Jul 2022
Dr. Sleep
S5E12 / 20 Jul 2022
The Road Warrior
S5E13 / 27 Jul 2022
My Fair Chipette
S5E14 / 28 Jul 2022
Gone Gal
S5E15 / 03 Aug 2022
Time Travelers Party
S5E16 / 04 Aug 2022
The House on Cedar Lane
S5E17 / 10 Aug 2022
Bathroom Bully
S5E18 / 11 Aug 2022
The Return of Thornbergaupht
S5E19 / 17 Aug 2022
Squashed
S5E20 / 18 Aug 2022
Writers Block
S5E21 / 24 Aug 2022
Jinxed
S5E22 / 25 Aug 2022
Fire Safety
S5E23 / 31 Aug 2022
Castle Catastrophe
S5E24 / 01 Sep 2022
The Party Animals
S5E25 / 07 Sep 2022
Warren Seville
S5E26 / 08 Sep 2022
Excavation Vacation
S5E27 / 14 Sep 2022
Trophy Dad
S5E28 / 15 Sep 2022
Skater Girl
S5E29 / 21 Sep 2022
All Washed Up
S5E30 / 22 Sep 2022
Summer School
S5E31 / 28 Sep 2022
Puzzled
S5E32 / 29 Sep 2022
Car Wars
S5E33 / 05 Oct 2022
Mr. Fix-It
S5E34 / 06 Oct 2022
Little Drummer Boy
S5E35 / 12 Oct 2022
Special Ingredient
S5E36 / 13 Oct 2022
Alvin Gets Schooled
S5E37 / 19 Oct 2022
My Life as a Dog
S5E38 / 20 Oct 2022
Mr. Lou
S5E39 / 26 Oct 2022
Love Song
S5E40 / 27 Oct 2022
Bubble Wrap
S5E41 / 02 Nov 2022
Chess Mate
S5E42 / 03 Nov 2022
A Knight's Tail
S5E43 / 09 Nov 2022
Dreambomber
S5E44 / 10 Nov 2022
The Lifeguard
S5E45 / 16 Nov 2022
Scare-Crowner
S5E46 / 17 Nov 2022
Run, Aimee, Run
S5E47 / 23 Nov 2022
Theo Vs. Simon
S5E48 / 24 Nov 2022
The Underground
S5E49 / 30 Nov 2022
The Dinner
S5E50 / 07 Dec 2022
Game House
S5E51 / 01 Dec 2022
The Tour
S5E52 / 08 Dec 2022
Ross Bagdasarian Jr.
Alvin Seville (Voice) / Simon Seville (Voice) / Dave Seville (Voice)
