Atar cabos

[ROBINDESBOIS]

In English?

[Marsopa]

Something like: to put two and two together...

or maybe "tie things up, tie up the loose ends"

[Tomisimo]

tie up the loose ends"
I'd go with this one.

See also: Atar cabos sueltos (http://www.tomisimo.org/idioms/es/atar-los-cabos-sueltos-3527.html).