But I do remember the story to an extent.
>its like the 1920s
>two twin or very near age sister & brother
>dad is some sort of sleuth or conspiratorial agent
>dad goes missing I think?
>kids look for him and find cool maps n' shit
>find him? I think?
>also found the treasure everyone was looking for too
These books also came with some really badass illustrations and even diagrams of rotating/hidden book shelves and ciphers. If memory also serves me right there were three books in this series. I read these back in 8th grade so this is all I can remember. Hope thats enough.
bump?
>>7588059
Oh I remember these! Operation Red Jericho
>>7589954
HOLY FUCKING SHIT! THANK YOU SO MUCH ANON!
and the second book
and the third
>>7588059
Spy Kids
>>7591517
top kek