Missing Link (1999)

Bright, dynamic Dutch schoolboy Rick Veenema (11) must grow up in a Frisian rural town without his father, a fallen Canadian pilot according to his single mother Lydia, who raises him with lazy, in-living aunt Wally. Fascinated by an atlas, which mother later reveals was his father's last souvenir, he gets obsessed with anthropology, and fights teacher or mother trying to take the 'distraction' away. Reading about a Belgian expedition to look for the evolutionary missing link in the Congo, Rick decides to join, or at least explain to supervising, Dutch professor Eduard Oudeweetering why he thinks they look in the wrong province. He 'escapes' with the naughty help of a resourceful neighbor girl, whose father Jef sets chase, just as his mother who reported him missing to the police. They'll meet in Brussels, after Rick has read mother's diary, which was locked up with the atlas, and tells he's actually the son of a Dutch resistance hero Eduard, who believed his wife deported, but got her back before Lydia, who had become his maid and lover, could disclose her pregnancy.