Grammar notes
If you want to say “That is the house that Jack built” the Russian word you need is ‘который’. Который agrees in number and gender with the noun to which it relates: Вот дом, которЫЙ построил Джек. А это пшеница, которая в темном чулане хранится, в доме, который построил Джек. Который also has case endings, but these depend not on the preceding noun but on the role of ‘который’ in its own clause. So in the Вот дом, которЫЙ (accusative) построил Джек the relative ‘который’ has an accusative ending because it is the object of ‘построил’. It is curious that English makes a distinction here between animate (the woman who…) and inanimate (the book which…) while Russian doesn’t, e.g. 'женщина, которую я люблю' or 'книга, которую я читаю'. In English ‘which/who/whom’ can be omitted, but in standard Russian relative word with a stem ‘котор-’ must always be presented in such sentences.