The series appears to be the cubes of consecutive numbers, but with a missing value. 1 = 1³, 8 = 2³, 27 = 3³. It is highly likely the image represents $1^3$, $2^3$, $3^3$, and $4^3$. The question mark would be $4^3 = 64$. However, the numbers are placed in a grid. 1 and 27 are top-left and bottom-right. 8 is top-right. The missing number is bottom-left. This could be a different pattern. Let's assume the initial assessment is correct: $1^3, 2^3, 3^3, 4^3$. The missing number in the sequence should be 64.