What happend in chapter 18 of The Secret Garden?

They did NOT find COLIN DEAD. Mary meets Dickon in the garden. In addition to Soot, his crow, and Captain, his fox, he has with him his pony, Jump, and two tame squirrels, Nut and Shell. Mary tells Dickon about Colin. ... Then in a bit, Dickon can push his chair and take him outside, and they will show him the garden.