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Series / Robert Arthur Jr.

Cover of The Secret of Terror Castle

The Three Investigators books in order A series by Robert Arthur Jr.

The Three Investigators series by Robert Arthur Jr. has 11 books (8 novels and 3 shorter works), from The Secret of Terror Castle (1964) to The Mystery of Phantom Lake (1973). Read it in order, starting with The Secret of Terror Castle.

Reading order: 1 The Secret of Terror Castle (1964) · 2 The Mystery of the Stuttering Parrot (1964) · 3 The Mystery of the Whispering Mummy (1965) · 4 The Mystery of the Green Ghost (1965) · 5 The Mystery of the Vanishing Treasure (1966) · 6 The Secret of Skeleton Island (1966) · 7 The Mystery of the Fiery Eye (1967) · 8 The Mystery of the Silver Spider (1967) · 11 The Mystery of the Talking Skull (1969) · 12 The Secret of the Crooked Cat (1970) · … all 11 below

Updated September 2026

All 11 The Three Investigators books in order

  1. 1.

    The Secret of Terror Castle (1964)

    165 pages

    Buy
  2. 2.

    The Mystery of the Stuttering Parrot (1964)

    169 pages

    Buy
  3. 3.

    The Mystery of the Whispering Mummy (1965)

    160 pages

    Buy
  4. 4.

    The Mystery of the Green Ghost (1965)

    172 pages

    Buy
  5. 5.

    The Mystery of the Vanishing Treasure (1966)

    152 pages

    Buy
  6. 6.

    The Secret of Skeleton Island (1966)

    158 pages

    Buy
  7. 7.

    The Mystery of the Fiery Eye (1967)

    149 pages

    Buy
  8. 8.

    The Mystery of the Silver Spider (1967)

    149 pages

    Buy
  9. 11.

    The Mystery of the Talking Skull (1969)

    162 pages

    Buy
  10. 12.

    The Secret of the Crooked Cat (1970)

    168 pages

    Buy
  11. 19.

    The Mystery of Phantom Lake (1973)

    Buy

The Three Investigators FAQ

How many The Three Investigators books are there?
There are 11 The Three Investigators books, as of September 2026.
What order should I read the The Three Investigators books in?
In publication order, starting with The Secret of Terror Castle (1964): 1 The Secret of Terror Castle (1964) · 2 The Mystery of the Stuttering Parrot (1964) · 3 The Mystery of the Whispering Mummy (1965) · 4 The Mystery of the Green Ghost (1965) · 5 The Mystery of the Vanishing Treasure (1966) · 6 The Secret of Skeleton Island (1966) · … all 11 below.
What is the first The Three Investigators book?
The Secret of Terror Castle (1964).
What is the latest The Three Investigators book?
The Mystery of Phantom Lake (1973).
Is the Three Investigators series finished?
There have been no new The Three Investigators books since 1973; Robert Arthur Jr. died in 1969.

Sources: series order and dates from Wikidata and Open Library. Last updated September 2026.