The 39 Clues Wiki
The 39 Clues Wiki

The Master Serum is made up of four incomplete Serums, each belonging to a branch. Gideon Cahill hid the master Serum from Damien Vesper and split the unfinished Serum into four parts—the four branch Serums. He gave each of the Serums to each of his four children, according to their strengths. It altered and enhanced their DNA, giving them each the different skills their branches are known for.

Branch Serum List[]

Serum Ingredients[]

Ekaterina Serum[]

The Ekaterinas have 7 ingredients for their serum.

Lucian Serum[]

The Lucians have 7 ingredients for their serum.

Janus Serum[]

The Janus have 8 ingredients for their serum.

Tomas Serum[]

The Tomas have 9 ingredients for their serum.

Madrigal Serum[]

There is no Madrigal serum, but there are Madrigal Clues. These ingredients are needed to make the safe master serum. Without them, The Master Serum is deadly.

Side Effects and Amounts[]

The Serums have demonstrated negative side effects when taken. After Isabel Kabra drank the Lucian Serum, her unfeeling sociopathy intensified. It is debatable as to whether or not that particular side effect would only appear in Cahills that drank their own branch's Serum, as drinking the Serum of your own branch would, theoretically, cause your already enhanced qualities to intensify further. If this is true, then when Isabel Kabra, who was already ruthless and unfeeling, drank the Lucian Serum, her terrible qualities simply increased and intensified. However, if persons from a different branch, like the Tomas, drank it, theoretically, they would receive the qualities of a Lucian without great harm because they never did have the qualities of the Lucians.

Another theory is that only a drop or two of the Serum is supposed to be drunk, as stated in The Viper's Nest, and various cards about Shaka Zulu. Shaka Zulu obtained a drop of the remaining Tomas Serum, and his abilities intensified without apparent harm. When Isabel drank the Lucian serum, she may have drunk it all and was put off-balance by the amount she drank. This theory is also reinforced by the fact that in Into the Gauntlet, the Serum Formula stated that only fractions of each branch Serum were needed to make the Master Serum.